diff --git a/.gitignore b/.gitignore
index 7f6220cf..089600eb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,4 +7,5 @@ bundle.js
 target
 lib
 *.tar.gz
-.eslintcache
\ No newline at end of file
+.eslintcache
+.tmp
diff --git a/package.json b/package.json
index e356347b..875766f8 100644
--- a/package.json
+++ b/package.json
@@ -10,7 +10,7 @@
     "lint-ts": "eslint src/ -c .ts-eslintrc.js --ext .ts",
     "lint-ci": "eslint src/",
     "test": "impunity --entry-point src/platform/web/main.js src/platform/web/Platform.js --force-esm-dirs lib/ src/ --root-dir src/",
-    "test:postcss": "impunity --entry-point  scripts/postcss/test.js ",
+    "test:postcss": "impunity --entry-point  scripts/postcss/tests/css-compile-variables.test.js scripts/postcss/tests/css-url-to-variables.test.js",
     "start": "vite --port 3000",
     "build": "vite build",
     "build:sdk": "./scripts/sdk/build.sh"
@@ -43,6 +43,7 @@
     "node-html-parser": "^4.0.0",
     "postcss-css-variables": "^0.18.0",
     "postcss-flexbugs-fixes": "^5.0.2",
+    "postcss-value-parser": "^4.2.0",
     "regenerator-runtime": "^0.13.7",
     "text-encoding": "^0.7.0",
     "typescript": "^4.4",
@@ -54,7 +55,6 @@
     "another-json": "^0.2.0",
     "base64-arraybuffer": "^0.2.0",
     "dompurify": "^2.3.0",
-    "off-color": "^2.0.0",
-    "postcss-value-parser": "^4.2.0"
+    "off-color": "^2.0.0"
   }
 }
diff --git a/scripts/build-plugins/rollup-plugin-build-themes.js b/scripts/build-plugins/rollup-plugin-build-themes.js
new file mode 100644
index 00000000..74fe4daf
--- /dev/null
+++ b/scripts/build-plugins/rollup-plugin-build-themes.js
@@ -0,0 +1,174 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+async function readCSSSource(location) {
+    const fs = require("fs").promises;
+    const path = require("path");
+    const resolvedLocation = path.resolve(__dirname, "../../",  `${location}/theme.css`);
+    const data = await fs.readFile(resolvedLocation);
+    return data;
+}
+
+async function appendVariablesToCSS(variables, cssSource) {
+    return cssSource + `:root{\n${Object.entries(variables).reduce((acc, [key, value]) => acc + `--${key}: ${value};\n`, "")} }\n\n`;
+}
+
+function parseBundle(bundle) {
+    const chunkMap = new Map();
+    const assetMap = new Map();
+    let runtimeThemeChunk;
+    for (const [fileName, info] of Object.entries(bundle)) {
+        if (!fileName.endsWith(".css")) {
+            continue;
+        }
+        if (info.type === "asset") {
+            /**
+             * So this is the css assetInfo that contains the asset hashed file name.
+             * We'll store it in a separate map indexed via fileName (unhashed) to avoid
+             * searching through the bundle array later.
+             */
+            assetMap.set(info.name, info);
+            continue;
+        }
+        if (info.facadeModuleId?.includes("type=runtime")) {
+            /**
+             * We have a separate field in manifest.source just for the runtime theme,
+             * so store this separately.
+             */
+            runtimeThemeChunk = info;
+            continue;
+        }
+        const location = info.facadeModuleId?.match(/(.+)\/.+\.css/)?.[1];
+        if (!location) {
+            throw new Error("Cannot find location of css chunk!");
+        }
+        const array = chunkMap.get(location);
+        if (!array) {
+            chunkMap.set(location, [info]);
+        }
+        else {
+            array.push(info);
+        }
+    }
+    return { chunkMap, assetMap, runtimeThemeChunk };
+}
+
+module.exports = function buildThemes(options) {
+    let manifest, variants, defaultDark, defaultLight;
+
+    return {
+        name: "build-themes",
+        enforce: "pre",
+
+        async buildStart() {
+            const { manifestLocations } = options;
+            for (const location of manifestLocations) {
+                manifest = require(`${location}/manifest.json`);
+                variants = manifest.values.variants;
+                const themeName = manifest.name;
+                for (const [variant, details] of Object.entries(variants)) {
+                    const fileName = `theme-${themeName}-${variant}.css`;
+                    if (details.default) {
+                        // This is one of the default variants for this theme.
+                        if (details.dark) {
+                            defaultDark = fileName;
+                        }
+                        else {
+                            defaultLight = fileName;
+                        }
+                    }
+                    // emit the css as built theme bundle
+                    this.emitFile({
+                        type: "chunk",
+                        id: `${location}/theme.css?variant=${variant}`,
+                        fileName,
+                    });
+                }
+                // emit the css as runtime theme bundle
+                this.emitFile({
+                    type: "chunk",
+                    id: `${location}/theme.css?type=runtime`,
+                    fileName: `theme-${themeName}-runtime.css`,
+                });
+            }
+        },
+
+        async load(id) {
+            const result = id.match(/(.+)\/theme.css\?variant=(.+)/);
+            if (result) {
+                const [, location, variant] = result;
+                const cssSource = await readCSSSource(location);
+                const config = variants[variant];
+                return await appendVariablesToCSS(config.variables, cssSource);
+            }
+            return null;
+        },
+
+        transformIndexHtml(_, ctx) {
+            let darkThemeLocation, lightThemeLocation;
+            for (const [, bundle] of Object.entries(ctx.bundle)) {
+                if (bundle.name === defaultDark) {
+                    darkThemeLocation = bundle.fileName;
+                }
+                if (bundle.name === defaultLight) {
+                    lightThemeLocation = bundle.fileName;
+                }
+            }
+            return [
+                {
+                    tag: "link",
+                    attrs: {
+                        rel: "stylesheet",
+                        type: "text/css",
+                        media: "(prefers-color-scheme: dark)",
+                        href: `./${darkThemeLocation}`,
+                    }
+                },
+                {
+                    tag: "link",
+                    attrs: {
+                        rel: "stylesheet",
+                        type: "text/css",
+                        media: "(prefers-color-scheme: light)",
+                        href: `./${lightThemeLocation}`,
+                    }
+                },
+            ];
+        },
+
+        generateBundle(_, bundle) {
+            const { assetMap, chunkMap, runtimeThemeChunk } = parseBundle(bundle);
+            for (const [location, chunkArray] of chunkMap) {
+                const manifest = require(`${location}/manifest.json`);
+                const compiledVariables = options.compiledVariables.get(location);
+                const derivedVariables = compiledVariables["derived-variables"];
+                const icon = compiledVariables["icon"];
+                manifest.source = {
+                    "built-asset": chunkArray.map(chunk => assetMap.get(chunk.fileName).fileName),
+                    "runtime-asset": assetMap.get(runtimeThemeChunk.fileName).fileName,
+                    "derived-variables": derivedVariables,
+                    "icon": icon
+                };
+                const name = `theme-${manifest.name}.json`;
+                this.emitFile({
+                    type: "asset",
+                    name,
+                    source: JSON.stringify(manifest),
+                });
+            }
+        }
+    }
+}
diff --git a/scripts/postcss/css-compile-variables.js b/scripts/postcss/css-compile-variables.js
index 3ed34513..fa584caa 100644
--- a/scripts/postcss/css-compile-variables.js
+++ b/scripts/postcss/css-compile-variables.js
@@ -43,17 +43,32 @@ function parseDeclarationValue(value) {
     const parsed = valueParser(value);
     const variables = [];
     parsed.walk(node => {
-        if (node.type !== "function" && node.value !== "var") {
+        if (node.type !== "function") {
             return;
         }
-        const variable = node.nodes[0];
-        variables.push(variable.value);
+        switch (node.value) {
+            case "var": {
+                const variable = node.nodes[0];
+                variables.push(variable.value);
+                break;
+            }
+            case "url": {
+                const url = node.nodes[0].value;
+                // resolve url with some absolute url so that we get the query params without using regex
+                const params = new URL(url, "file://foo/bar/").searchParams;
+                const primary = params.get("primary");
+                const secondary = params.get("secondary");
+                if (primary) { variables.push(primary); }
+                if (secondary) { variables.push(secondary); }
+                break;
+            }
+        }
     });
     return variables;
 }
 
 function resolveDerivedVariable(decl, derive) {
-    const RE_VARIABLE_VALUE = /--((.+)--(.+)-(.+))/;
+    const RE_VARIABLE_VALUE = /(?:--)?((.+)--(.+)-(.+))/;
     const variableCollection = parseDeclarationValue(decl.value);
     for (const variable of variableCollection) {
         const matches = variable.match(RE_VARIABLE_VALUE);
@@ -94,6 +109,15 @@ function addResolvedVariablesToRootSelector(root, {Rule, Declaration}) {
     root.append(newRule);
 }
 
+function populateMapWithDerivedVariables(map, cssFileLocation) {
+    const location = cssFileLocation.match(/(.+)\/.+\.css/)?.[1];
+    const derivedVariables = [
+        ...([...resolvedMap.keys()].filter(v => !aliasMap.has(v))),
+        ...([...aliasMap.entries()].map(([alias, variable]) => `${alias}=${variable}`))
+    ];
+    map.set(location, { "derived-variables": derivedVariables });
+}
+
 /**
  * @callback derive
  * @param {string} value - The base value on which an operation is applied
@@ -104,6 +128,7 @@ function addResolvedVariablesToRootSelector(root, {Rule, Declaration}) {
  * 
  * @param {Object} opts - Options for the plugin
  * @param {derive} opts.derive - The callback which contains the logic for resolving derived variables
+ * @param {Map} opts.compiledVariables - A map that stores derived variables so that manifest source sections can be produced
  */
 module.exports = (opts = {}) => {
     aliasMap = new Map();
@@ -112,7 +137,12 @@ module.exports = (opts = {}) => {
     return {
         postcssPlugin: "postcss-compile-variables",
 
-        Once(root, {Rule, Declaration}) {
+        Once(root, {Rule, Declaration, result}) {
+            const cssFileLocation = root.source.input.from;
+            if (cssFileLocation.includes("type=runtime")) {
+                // If this is a runtime theme, don't derive variables.
+                return;
+            }
             /*
             Go through the CSS file once to extract all aliases and base variables.
             We use these when resolving derived variables later.
@@ -120,6 +150,16 @@ module.exports = (opts = {}) => {
             root.walkDecls(decl => extract(decl));
             root.walkDecls(decl => resolveDerivedVariable(decl, opts.derive));
             addResolvedVariablesToRootSelector(root, {Rule, Declaration});
+            if (opts.compiledVariables){
+                populateMapWithDerivedVariables(opts.compiledVariables, cssFileLocation);
+            }
+            // Publish both the base-variables and derived-variables to the other postcss-plugins
+            const combinedMap = new Map([...baseVariables, ...resolvedMap]);
+            result.messages.push({
+                type: "resolved-variable-map",
+                plugin: "postcss-compile-variables",
+                colorMap: combinedMap,
+            });
         },
     };
 };
diff --git a/scripts/postcss/css-url-processor.js b/scripts/postcss/css-url-processor.js
new file mode 100644
index 00000000..1a0e4fdf
--- /dev/null
+++ b/scripts/postcss/css-url-processor.js
@@ -0,0 +1,87 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+const valueParser = require("postcss-value-parser");
+const  resolve = require("path").resolve;
+
+function colorsFromURL(url, colorMap) {
+    const params = new URL(`file://${url}`).searchParams;
+    const primary = params.get("primary");
+    if (!primary) {
+        return null;
+    }
+    const secondary = params.get("secondary");
+    const primaryColor = colorMap.get(primary);
+    const secondaryColor = colorMap.get(secondary);
+    if (!primaryColor) {
+        throw new Error(`Variable ${primary} not found in resolved color variables!`);
+    }
+    if (secondary && !secondaryColor) {
+        throw new Error(`Variable ${secondary} not found in resolved color variables!`);
+    }
+    return [primaryColor, secondaryColor];
+}
+
+function processURL(decl, replacer, colorMap) {
+    const value = decl.value;
+    const parsed = valueParser(value);
+    parsed.walk(async node => {
+        if (node.type !== "function" || node.value !== "url") {
+            return;
+        }
+        const urlStringNode = node.nodes[0];
+        const oldURL = urlStringNode.value;
+        const cssPath = decl.source?.input.file.replace(/[^/]*$/, "");
+        const oldURLAbsolute = resolve(cssPath, oldURL);
+        const colors  = colorsFromURL(oldURLAbsolute, colorMap);
+        if (!colors) {
+            // If no primary color is provided via url params, then this url need not be handled.
+            return;
+        }
+        const newURL = replacer(oldURLAbsolute.replace(/\?.+/, ""), ...colors);
+        if (!newURL) {
+            throw new Error("Replacer failed to produce a replacement URL!");
+        }
+        urlStringNode.value = newURL;
+    });
+    decl.assign({prop: decl.prop, value: parsed.toString()})
+}
+
+/* *
+ * @type {import('postcss').PluginCreator}
+ */
+module.exports = (opts = {}) => {
+    return {
+        postcssPlugin: "postcss-url-to-variable",
+
+        Once(root, {result}) {
+            /*
+            postcss-compile-variables should have sent the list of resolved colours down via results
+            */
+            const {colorMap} = result.messages.find(m => m.type === "resolved-variable-map");
+            if (!colorMap) {
+                throw new Error("Postcss results do not contain resolved colors!");
+            }
+            /*
+            Go through each declaration and if it contains an URL, replace the url with the result
+            of running replacer(url)
+            */
+            root.walkDecls(decl => processURL(decl, opts.replacer, colorMap));
+        },
+    };
+};
+
+module.exports.postcss = true;
diff --git a/scripts/postcss/css-url-to-variables.js b/scripts/postcss/css-url-to-variables.js
new file mode 100644
index 00000000..1d4666f4
--- /dev/null
+++ b/scripts/postcss/css-url-to-variables.js
@@ -0,0 +1,85 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+const valueParser = require("postcss-value-parser");
+
+/**
+ * This plugin extracts content inside url() into css variables and adds the variables to the root section.
+ * This plugin is used in conjunction with css-url-processor plugin to colorize svg icons.
+ */
+let counter;
+let urlVariables;
+const idToPrepend = "icon-url";
+
+function findAndReplaceUrl(decl) {
+    const value = decl.value;
+    const parsed = valueParser(value);
+    parsed.walk(node => {
+        if (node.type !== "function" || node.value !== "url") {
+            return;
+        }
+        const url = node.nodes[0].value;
+        if (!url.match(/\.svg\?primary=.+/)) {
+            return;
+        }
+        const variableName = `${idToPrepend}-${counter++}`;
+        urlVariables.set(variableName, url);
+        node.value = "var";
+        node.nodes = [{ type: "word", value: `--${variableName}` }];
+    });
+    decl.assign({prop: decl.prop, value: parsed.toString()})
+}
+
+function addResolvedVariablesToRootSelector(root, { Rule, Declaration }) {
+    const newRule = new Rule({ selector: ":root", source: root.source });
+    // Add derived css variables to :root
+    urlVariables.forEach((value, key) => {
+        const declaration = new Declaration({ prop: `--${key}`, value: `url("${value}")`});
+        newRule.append(declaration);
+    });
+    root.append(newRule);
+}
+
+function populateMapWithIcons(map, cssFileLocation) {
+    const location = cssFileLocation.match(/(.+)\/.+\.css/)?.[1];
+    const sharedObject = map.get(location);
+    sharedObject["icon"] = Object.fromEntries(urlVariables);
+}
+
+/* *
+ * @type {import('postcss').PluginCreator}
+ */
+module.exports = (opts = {}) => {
+    urlVariables = new Map();
+    counter = 0;
+    return {
+        postcssPlugin: "postcss-url-to-variable",
+
+        Once(root, { Rule, Declaration }) {
+            root.walkDecls(decl => findAndReplaceUrl(decl));
+            if (urlVariables.size) {
+                addResolvedVariablesToRootSelector(root, { Rule, Declaration });
+            }
+            if (opts.compiledVariables){
+                const cssFileLocation = root.source.input.from;
+                populateMapWithIcons(opts.compiledVariables, cssFileLocation);
+            }
+        },
+    };
+};
+
+module.exports.postcss = true;
+
diff --git a/scripts/postcss/svg-colorizer.js b/scripts/postcss/svg-colorizer.js
new file mode 100644
index 00000000..7d527ddb
--- /dev/null
+++ b/scripts/postcss/svg-colorizer.js
@@ -0,0 +1,45 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+const fs = require("fs");
+const path = require("path");
+/**
+ * Builds a new svg with the colors replaced and returns its location.
+ * @param {string} svgLocation The location of the input svg file
+ * @param {string} primaryColor Primary color for the new svg
+ * @param {string} secondaryColor Secondary color for the new svg
+ */
+module.exports.buildColorizedSVG = function (svgLocation, primaryColor, secondaryColor) {
+    const svgCode = fs.readFileSync(svgLocation, { encoding: "utf8"});
+    let coloredSVGCode = svgCode.replaceAll("#ff00ff", primaryColor);
+    coloredSVGCode = coloredSVGCode.replaceAll("#00ffff", secondaryColor);
+    if (svgCode === coloredSVGCode) {
+        throw new Error("svg-colorizer made no color replacements! The input svg should only contain colors #ff00ff (primary, case-sensitive) and #00ffff (secondary, case-sensitive).");
+    }
+    const fileName = svgLocation.match(/.+\/(.+\.svg)/)[1];
+    const outputPath = path.resolve(__dirname, "../../.tmp");
+    try {
+       fs.mkdirSync(outputPath);
+    }
+    catch (e) {
+        if (e.code !== "EEXIST") {
+            throw e;
+        }
+    }
+    const outputFile = `${outputPath}/${fileName}`;
+    fs.writeFileSync(outputFile, coloredSVGCode);
+    return outputFile;
+}
diff --git a/scripts/postcss/tests/common.js b/scripts/postcss/tests/common.js
new file mode 100644
index 00000000..78ae847e
--- /dev/null
+++ b/scripts/postcss/tests/common.js
@@ -0,0 +1,30 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+const postcss = require("postcss");
+
+module.exports.createTestRunner = function (plugin) {
+    return async function run(input, output, opts = {}, assert) {
+        let result = await postcss([plugin(opts)]).process(input, { from: undefined, });
+        assert.strictEqual(
+            result.css.replaceAll(/\s/g, ""),
+            output.replaceAll(/\s/g, "")
+        );
+        assert.strictEqual(result.warnings().length, 0);
+    };
+}
+
+
diff --git a/scripts/postcss/test.js b/scripts/postcss/tests/css-compile-variables.test.js
similarity index 64%
rename from scripts/postcss/test.js
rename to scripts/postcss/tests/css-compile-variables.test.js
index 36ff9282..e40751db 100644
--- a/scripts/postcss/test.js
+++ b/scripts/postcss/tests/css-compile-variables.test.js
@@ -16,17 +16,9 @@ limitations under the License.
 
 const offColor = require("off-color").offColor;
 const postcss = require("postcss");
-const plugin = require("./css-compile-variables");
-const derive = require("./color").derive;
-
-async function run(input, output, opts = {}, assert) {
-    let result = await postcss([plugin({ ...opts, derive })]).process(input, { from: undefined, });
-    assert.strictEqual(
-        result.css.replaceAll(/\s/g, ""),
-        output.replaceAll(/\s/g, "")
-    );
-    assert.strictEqual(result.warnings().length, 0);
-}
+const plugin = require("../css-compile-variables");
+const derive = require("../color").derive;
+const run = require("./common").createTestRunner(plugin);
 
 module.exports.tests = function tests() {
     return {
@@ -46,7 +38,7 @@ module.exports.tests = function tests() {
                 --foo-color--lighter-50: ${transformedColor.hex()};
             }
             `;
-            await run( inputCSS, outputCSS, {}, assert);
+            await run( inputCSS, outputCSS, {derive}, assert);
         },
 
         "derived variables work with alias": async (assert) => {
@@ -66,7 +58,7 @@ module.exports.tests = function tests() {
                 --my-alias--lighter-15: ${aliasLighter};
             }
             `;
-            await run(inputCSS, outputCSS, { }, assert);
+            await run(inputCSS, outputCSS, {derive}, assert);
         },
 
         "derived variable throws if base not present in config": async (assert) => {
@@ -94,8 +86,9 @@ module.exports.tests = function tests() {
                 --foo-color--darker-20: ${transformedColor2.hex()};
             }
             `;
-            await run( inputCSS, outputCSS, { }, assert);
+            await run( inputCSS, outputCSS, {derive}, assert);
         },
+
         "multiple aliased-derived variable in single declaration is parsed correctly": async (assert) => {
             const inputCSS = `
             :root {
@@ -115,7 +108,49 @@ module.exports.tests = function tests() {
                 --my-alias--darker-20: ${transformedColor2.hex()};
             }
             `;
-            await run( inputCSS, outputCSS, { }, assert);
+            await run( inputCSS, outputCSS, {derive}, assert);
+        },
+
+        "compiledVariables map is populated": async (assert) => {
+            const compiledVariables = new Map();
+            const inputCSS = `
+            :root {
+                --icon-color: #fff;
+            }
+            div {
+                background: var(--icon-color--darker-20);
+                --my-alias: var(--icon-color--darker-20);
+                color: var(--my-alias--lighter-15);
+            }`;
+            await postcss([plugin({ derive, compiledVariables })]).process(inputCSS, { from: "/foo/bar/test.css", });
+            const actualArray = compiledVariables.get("/foo/bar")["derived-variables"];
+            const expectedArray = ["icon-color--darker-20", "my-alias=icon-color--darker-20", "my-alias--lighter-15"];
+            assert.deepStrictEqual(actualArray.sort(), expectedArray.sort());
+        },
+
+        "derived variable are supported in urls": async (assert) => {
+            const inputCSS = `
+            :root {
+                --foo-color: #ff0;
+            }
+            div {
+                background-color: var(--foo-color--lighter-50);
+                background: url("./foo/bar/icon.svg?primary=foo-color--darker-5");
+            }
+            a {
+                background: url("foo/bar/icon.svg");
+            }`;
+            const transformedColorLighter = offColor("#ff0").lighten(0.5);
+            const transformedColorDarker = offColor("#ff0").darken(0.05);
+            const outputCSS =
+                inputCSS +
+                `
+            :root {
+                --foo-color--lighter-50: ${transformedColorLighter.hex()};
+                --foo-color--darker-5: ${transformedColorDarker.hex()};
+            }
+            `;
+            await run( inputCSS, outputCSS, {derive}, assert);
         }
     };
 };
diff --git a/scripts/postcss/tests/css-url-to-variables.test.js b/scripts/postcss/tests/css-url-to-variables.test.js
new file mode 100644
index 00000000..f406a38a
--- /dev/null
+++ b/scripts/postcss/tests/css-url-to-variables.test.js
@@ -0,0 +1,71 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+const plugin = require("../css-url-to-variables");
+const run = require("./common").createTestRunner(plugin);
+const postcss = require("postcss");
+
+module.exports.tests = function tests() {
+    return {
+        "url is replaced with variable": async (assert) => {
+            const inputCSS = `div {
+                background: no-repeat center/80% url("../img/image.svg?primary=main-color--darker-20");
+            }
+            button {
+                background: url("/home/foo/bar/cool.svg?primary=blue&secondary=green");
+            }`;
+            const outputCSS =
+            `div {
+                background: no-repeat center/80% var(--icon-url-0);
+            }
+            button {
+                background: var(--icon-url-1);
+            }`+
+                `
+            :root {
+                --icon-url-0: url("../img/image.svg?primary=main-color--darker-20");
+                --icon-url-1: url("/home/foo/bar/cool.svg?primary=blue&secondary=green");
+            }
+            `;
+            await run(inputCSS, outputCSS, { }, assert);
+        },
+        "non svg urls without query params are not replaced": async (assert) => {
+            const inputCSS = `div {
+                background: no-repeat url("./img/foo/bar/image.png");
+            }`;
+            await run(inputCSS, inputCSS, {}, assert);
+        },
+        "map is populated with icons": async (assert) => {
+            const compiledVariables = new Map();
+            compiledVariables.set("/foo/bar", { "derived-variables": ["background-color--darker-20", "accent-color--lighter-15"] });
+            const inputCSS = `div {
+                background: no-repeat center/80% url("../img/image.svg?primary=main-color--darker-20");
+            }
+            button {
+                background: url("/home/foo/bar/cool.svg?primary=blue&secondary=green");
+            }`;
+            const expectedObject = {
+                "icon-url-0": "../img/image.svg?primary=main-color--darker-20",
+                "icon-url-1": "/home/foo/bar/cool.svg?primary=blue&secondary=green",
+            };
+            await postcss([plugin({compiledVariables})]).process(inputCSS, { from: "/foo/bar/test.css", });
+            const sharedVariable = compiledVariables.get("/foo/bar");
+            assert.deepEqual(["background-color--darker-20", "accent-color--lighter-15"], sharedVariable["derived-variables"]);
+            assert.deepEqual(expectedObject, sharedVariable["icon"]);
+        }
+    };
+};
+
diff --git a/scripts/sdk/base-manifest.json b/scripts/sdk/base-manifest.json
index ba0e1f4f..7730bbac 100644
--- a/scripts/sdk/base-manifest.json
+++ b/scripts/sdk/base-manifest.json
@@ -1,7 +1,7 @@
 {
     "name": "hydrogen-view-sdk",
     "description": "Embeddable matrix client library, including view components",
-    "version": "0.0.9",
+    "version": "0.0.10",
     "main": "./hydrogen.es.js",
     "type": "module"
 }
diff --git a/src/domain/ViewModel.ts b/src/domain/ViewModel.ts
index cfe22326..8b8581ae 100644
--- a/src/domain/ViewModel.ts
+++ b/src/domain/ViewModel.ts
@@ -58,6 +58,14 @@ export class ViewModel<O extends Options = Options> extends EventEmitter<{change
         return this._options[name];
     }
 
+    observeNavigation(type: string, onChange: (value: string | true | undefined, type: string) => void) {
+      const segmentObservable = this.navigation.observe(type);
+      const unsubscribe = segmentObservable.subscribe((value: string | true | undefined) => {
+        onChange(value, type);
+      })
+      this.track(unsubscribe);
+    }
+
     track<D extends Disposable>(disposable: D): D {
         if (!this.disposables) {
             this.disposables = new Disposables();
diff --git a/src/domain/session/room/RoomViewModel.js b/src/domain/session/room/RoomViewModel.js
index c12ed3b8..e7d7dc9a 100644
--- a/src/domain/session/room/RoomViewModel.js
+++ b/src/domain/session/room/RoomViewModel.js
@@ -20,18 +20,21 @@ import {ComposerViewModel} from "./ComposerViewModel.js"
 import {CallViewModel} from "./CallViewModel"
 import {PickMapObservableValue} from "../../../observable/value/PickMapObservableValue";
 import {avatarInitials, getIdentifierColorNumber, getAvatarHttpUrl} from "../../avatar";
-import {tilesCreator} from "./timeline/tilesCreator.js";
 import {ViewModel} from "../../ViewModel";
 import {imageToInfo} from "../common.js";
 import {LocalMedia} from "../../../matrix/calls/LocalMedia";
+// TODO: remove fallback so default isn't included in bundle for SDK users that have their custom tileClassForEntry
+// this is a breaking SDK change though to make this option mandatory
+import {tileClassForEntry as defaultTileClassForEntry} from "./timeline/tiles/index";
 
 export class RoomViewModel extends ViewModel {
     constructor(options) {
         super(options);
-        const {room} = options;
+        const {room, tileClassForEntry} = options;
         this._room = room;
         this._timelineVM = null;
-        this._tilesCreator = null;
+        this._tileClassForEntry = tileClassForEntry ?? defaultTileClassForEntry;
+        this._tileOptions = undefined;
         this._onRoomChange = this._onRoomChange.bind(this);
         this._timelineError = null;
         this._sendError = null;
@@ -73,13 +76,14 @@ export class RoomViewModel extends ViewModel {
         this._room.on("change", this._onRoomChange);
         try {
             const timeline = await this._room.openTimeline();
-            this._tilesCreator = tilesCreator(this.childOptions({
+            this._tileOptions = this.childOptions({
                 session: this.getOption("session"),
                 roomVM: this,
                 timeline,
-            }));
+                tileClassForEntry: this._tileClassForEntry,
+            });
             this._timelineVM = this.track(new TimelineViewModel(this.childOptions({
-                tilesCreator: this._tilesCreator,
+                tileOptions: this._tileOptions,
                 timeline,
             })));
             this.emitChange("timelineViewModel");
@@ -189,7 +193,12 @@ export class RoomViewModel extends ViewModel {
     }
 
     _createTile(entry) {
-        return this._tilesCreator(entry);
+        if (this._tileOptions) {
+            const Tile = this._tileOptions.tileClassForEntry(entry);
+            if (Tile) {
+                return new Tile(entry, this._tileOptions);
+            }
+        }
     }
     
     async _sendMessage(message, replyingTo) {
diff --git a/src/domain/session/room/timeline/ReactionsViewModel.js b/src/domain/session/room/timeline/ReactionsViewModel.js
index 214ec17f..c6055d20 100644
--- a/src/domain/session/room/timeline/ReactionsViewModel.js
+++ b/src/domain/session/room/timeline/ReactionsViewModel.js
@@ -222,7 +222,7 @@ export function tests() {
         };
         const tiles = new MappedList(timeline.entries, entry => {
             if (entry.eventType === "m.room.message") {
-                return new BaseMessageTile({entry, roomVM: {room}, timeline, platform: {logger}});
+                return new BaseMessageTile(entry, {roomVM: {room}, timeline, platform: {logger}});
             }
             return null;
         }, (tile, params, entry) => tile?.updateEntry(entry, params, function () {}));
diff --git a/src/domain/session/room/timeline/TilesCollection.js b/src/domain/session/room/timeline/TilesCollection.js
index 33ae4472..173b0cf6 100644
--- a/src/domain/session/room/timeline/TilesCollection.js
+++ b/src/domain/session/room/timeline/TilesCollection.js
@@ -18,20 +18,27 @@ import {BaseObservableList} from "../../../../observable/list/BaseObservableList
 import {sortedIndex} from "../../../../utils/sortedIndex";
 
 // maps 1..n entries to 0..1 tile. Entries are what is stored in the timeline, either an event or fragmentboundary
-// for now, tileCreator should be stable in whether it returns a tile or not.
+// for now, tileClassForEntry should be stable in whether it returns a tile or not.
 // e.g. the decision to create a tile or not should be based on properties
 // not updated later on (e.g. event type)
 // also see big comment in onUpdate
 export class TilesCollection extends BaseObservableList {
-    constructor(entries, tileCreator) {
+    constructor(entries, tileOptions) {
         super();
         this._entries = entries;
         this._tiles = null;
         this._entrySubscription = null;
-        this._tileCreator = tileCreator;
+        this._tileOptions = tileOptions;
         this._emitSpontanousUpdate = this._emitSpontanousUpdate.bind(this);
     }
 
+    _createTile(entry) {
+        const Tile = this._tileOptions.tileClassForEntry(entry);
+        if (Tile) {
+            return new Tile(entry, this._tileOptions);
+        }
+    }
+
     _emitSpontanousUpdate(tile, params) {
         const entry = tile.lowerEntry;
         const tileIdx = this._findTileIdx(entry);
@@ -48,7 +55,7 @@ export class TilesCollection extends BaseObservableList {
         let currentTile = null;
         for (let entry of this._entries) {
             if (!currentTile || !currentTile.tryIncludeEntry(entry)) {
-                currentTile = this._tileCreator(entry);
+                currentTile = this._createTile(entry);
                 if (currentTile) {
                     this._tiles.push(currentTile);
                 }
@@ -121,7 +128,7 @@ export class TilesCollection extends BaseObservableList {
             return;
         }
 
-        const newTile = this._tileCreator(entry);
+        const newTile = this._createTile(entry);
         if (newTile) {
             if (prevTile) {
                 prevTile.updateNextSibling(newTile);
@@ -150,9 +157,9 @@ export class TilesCollection extends BaseObservableList {
         const tileIdx = this._findTileIdx(entry);
         const tile = this._findTileAtIdx(entry, tileIdx);
         if (tile) {
-            const action = tile.updateEntry(entry, params, this._tileCreator);
+            const action = tile.updateEntry(entry, params);
             if (action.shouldReplace) {
-                const newTile = this._tileCreator(entry);
+                const newTile = this._createTile(entry);
                 if (newTile) {
                     this._replaceTile(tileIdx, tile, newTile, action.updateParams);
                     newTile.setUpdateEmit(this._emitSpontanousUpdate);
@@ -303,7 +310,10 @@ export function tests() {
                 }
             }
             const entries = new ObservableArray([{n: 5}, {n: 10}]);
-            const tiles = new TilesCollection(entries, entry => new UpdateOnSiblingTile(entry));
+            const tileOptions = {
+                tileClassForEntry: () => UpdateOnSiblingTile,
+            };
+            const tiles = new TilesCollection(entries, tileOptions);
             let receivedAdd = false;
             tiles.subscribe({
                 onAdd(idx, tile) {
@@ -326,7 +336,10 @@ export function tests() {
                 }
             }
             const entries = new ObservableArray([{n: 5}, {n: 10}, {n: 15}]);
-            const tiles = new TilesCollection(entries, entry => new UpdateOnSiblingTile(entry));
+            const tileOptions = {
+                tileClassForEntry: () => UpdateOnSiblingTile,
+            };
+            const tiles = new TilesCollection(entries, tileOptions);
             const events = [];
             tiles.subscribe({
                 onUpdate(idx, tile) {
diff --git a/src/domain/session/room/timeline/TimelineViewModel.js b/src/domain/session/room/timeline/TimelineViewModel.js
index 2408146d..cf36fce4 100644
--- a/src/domain/session/room/timeline/TimelineViewModel.js
+++ b/src/domain/session/room/timeline/TimelineViewModel.js
@@ -37,9 +37,9 @@ import {ViewModel} from "../../../ViewModel";
 export class TimelineViewModel extends ViewModel {
     constructor(options) {
         super(options);
-        const {timeline, tilesCreator} = options;
+        const {timeline, tileOptions} = options;
         this._timeline = this.track(timeline);
-        this._tiles = new TilesCollection(timeline.entries, tilesCreator);
+        this._tiles = new TilesCollection(timeline.entries, tileOptions);
         this._startTile = null;
         this._endTile = null;
         this._topLoadingPromise = null;
diff --git a/src/domain/session/room/timeline/tiles/BaseMediaTile.js b/src/domain/session/room/timeline/tiles/BaseMediaTile.js
index a927d766..0ba5b9a9 100644
--- a/src/domain/session/room/timeline/tiles/BaseMediaTile.js
+++ b/src/domain/session/room/timeline/tiles/BaseMediaTile.js
@@ -21,8 +21,8 @@ const MAX_HEIGHT = 300;
 const MAX_WIDTH = 400;
 
 export class BaseMediaTile extends BaseMessageTile {
-    constructor(options) {
-        super(options);
+    constructor(entry, options) {
+        super(entry, options);
         this._decryptedThumbnail = null;
         this._decryptedFile = null;
         this._isVisible = false;
diff --git a/src/domain/session/room/timeline/tiles/BaseMessageTile.js b/src/domain/session/room/timeline/tiles/BaseMessageTile.js
index c2041a2c..5a28e1b3 100644
--- a/src/domain/session/room/timeline/tiles/BaseMessageTile.js
+++ b/src/domain/session/room/timeline/tiles/BaseMessageTile.js
@@ -19,8 +19,8 @@ import {ReactionsViewModel} from "../ReactionsViewModel.js";
 import {getIdentifierColorNumber, avatarInitials, getAvatarHttpUrl} from "../../../../avatar";
 
 export class BaseMessageTile extends SimpleTile {
-    constructor(options) {
-        super(options);
+    constructor(entry, options) {
+        super(entry, options);
         this._date = this._entry.timestamp ? new Date(this._entry.timestamp) : null;
         this._isContinuation = false;
         this._reactions = null;
@@ -28,7 +28,7 @@ export class BaseMessageTile extends SimpleTile {
         if (this._entry.annotations || this._entry.pendingAnnotations) {
             this._updateReactions();
         }
-        this._updateReplyTileIfNeeded(options.tilesCreator, undefined);
+        this._updateReplyTileIfNeeded(undefined);
     }
 
     notifyVisible() {
@@ -114,23 +114,27 @@ export class BaseMessageTile extends SimpleTile {
         }
     }
 
-    updateEntry(entry, param, tilesCreator) {
-        const action = super.updateEntry(entry, param, tilesCreator);
+    updateEntry(entry, param) {
+        const action = super.updateEntry(entry, param);
         if (action.shouldUpdate) {
             this._updateReactions();
         }
-        this._updateReplyTileIfNeeded(tilesCreator, param);
+        this._updateReplyTileIfNeeded(param);
         return action;
     }
 
-    _updateReplyTileIfNeeded(tilesCreator, param) {
+    _updateReplyTileIfNeeded(param) {
         const replyEntry = this._entry.contextEntry;
         if (replyEntry) {
             // this is an update to contextEntry used for replyPreview
-            const action = this._replyTile?.updateEntry(replyEntry, param, tilesCreator);
+            const action = this._replyTile?.updateEntry(replyEntry, param);
             if (action?.shouldReplace || !this._replyTile) {
                 this.disposeTracked(this._replyTile);
-                this._replyTile = tilesCreator(replyEntry);
+                const tileClassForEntry = this._options.tileClassForEntry;
+                const ReplyTile = tileClassForEntry(replyEntry);
+                if (ReplyTile) {
+                    this._replyTile = new ReplyTile(replyEntry, this._options);
+                }
             }
             if(action?.shouldUpdate) {
                 this._replyTile?.emitChange();
diff --git a/src/domain/session/room/timeline/tiles/BaseTextTile.js b/src/domain/session/room/timeline/tiles/BaseTextTile.js
index 164443e3..8e78c95f 100644
--- a/src/domain/session/room/timeline/tiles/BaseTextTile.js
+++ b/src/domain/session/room/timeline/tiles/BaseTextTile.js
@@ -21,8 +21,8 @@ import {createEnum} from "../../../../../utils/enum";
 export const BodyFormat = createEnum("Plain", "Html");
 
 export class BaseTextTile extends BaseMessageTile {
-    constructor(options) {
-        super(options);
+    constructor(entry, options) {
+        super(entry, options);
         this._messageBody = null;
         this._format = null
     }
diff --git a/src/domain/session/room/timeline/tiles/CallTile.js b/src/domain/session/room/timeline/tiles/CallTile.js
index 3e3918b6..32807958 100644
--- a/src/domain/session/room/timeline/tiles/CallTile.js
+++ b/src/domain/session/room/timeline/tiles/CallTile.js
@@ -23,9 +23,8 @@ import {LocalMedia} from "../../../../../matrix/calls/LocalMedia";
 // alternatively, we could just subscribe to the GroupCall and spontanously emit an update when it updates
 
 export class CallTile extends SimpleTile {
-
-    constructor(options) {
-        super(options);
+    constructor(entry, options) {
+        super(entry, options);
         const calls = this.getOption("session").callHandler.calls;
         this._call = calls.get(this._entry.stateKey);
         this._callSubscription = undefined;
diff --git a/src/domain/session/room/timeline/tiles/EncryptedEventTile.js b/src/domain/session/room/timeline/tiles/EncryptedEventTile.js
index 50f507eb..b96e2d85 100644
--- a/src/domain/session/room/timeline/tiles/EncryptedEventTile.js
+++ b/src/domain/session/room/timeline/tiles/EncryptedEventTile.js
@@ -18,8 +18,8 @@ import {BaseTextTile} from "./BaseTextTile.js";
 import {UpdateAction} from "../UpdateAction.js";
 
 export class EncryptedEventTile extends BaseTextTile {
-    updateEntry(entry, params, tilesCreator) {
-        const parentResult = super.updateEntry(entry, params, tilesCreator);
+    updateEntry(entry, params) {
+        const parentResult = super.updateEntry(entry, params);
         // event got decrypted, recreate the tile and replace this one with it
         if (entry.eventType !== "m.room.encrypted") {
             // the "shape" parameter trigger tile recreation in TimelineView
diff --git a/src/domain/session/room/timeline/tiles/FileTile.js b/src/domain/session/room/timeline/tiles/FileTile.js
index 1007d28c..3f7b539b 100644
--- a/src/domain/session/room/timeline/tiles/FileTile.js
+++ b/src/domain/session/room/timeline/tiles/FileTile.js
@@ -20,8 +20,8 @@ import {formatSize} from "../../../../../utils/formatSize";
 import {SendStatus} from "../../../../../matrix/room/sending/PendingEvent.js";
 
 export class FileTile extends BaseMessageTile {
-    constructor(options) {
-        super(options);
+    constructor(entry, options) {
+        super(entry, options);
         this._downloadError = null;
         this._downloading = false;
     }
diff --git a/src/domain/session/room/timeline/tiles/GapTile.js b/src/domain/session/room/timeline/tiles/GapTile.js
index df0cedd9..6caa4b9b 100644
--- a/src/domain/session/room/timeline/tiles/GapTile.js
+++ b/src/domain/session/room/timeline/tiles/GapTile.js
@@ -18,8 +18,8 @@ import {SimpleTile} from "./SimpleTile.js";
 import {UpdateAction} from "../UpdateAction.js";
 
 export class GapTile extends SimpleTile {
-    constructor(options) {
-        super(options);
+    constructor(entry, options) {
+        super(entry, options);
         this._loading = false;
         this._error = null;
         this._isAtTop = true;
@@ -81,8 +81,8 @@ export class GapTile extends SimpleTile {
         this._siblingChanged = true;
     }
 
-    updateEntry(entry, params, tilesCreator) {
-        super.updateEntry(entry, params, tilesCreator);
+    updateEntry(entry, params) {
+        super.updateEntry(entry, params);
         if (!entry.isGap) {
             return UpdateAction.Remove();
         } else {
@@ -125,7 +125,7 @@ export function tests() {
                     tile.updateEntry(newEntry);
                 }
             };
-            const tile = new GapTile({entry: new FragmentBoundaryEntry(fragment, true), roomVM: {room}});
+            const tile = new GapTile(new FragmentBoundaryEntry(fragment, true), {roomVM: {room}});
             await tile.fill();
             await tile.fill();
             await tile.fill();
diff --git a/src/domain/session/room/timeline/tiles/ImageTile.js b/src/domain/session/room/timeline/tiles/ImageTile.js
index eae2b926..dd959b28 100644
--- a/src/domain/session/room/timeline/tiles/ImageTile.js
+++ b/src/domain/session/room/timeline/tiles/ImageTile.js
@@ -18,8 +18,8 @@ limitations under the License.
 import {BaseMediaTile} from "./BaseMediaTile.js";
 
 export class ImageTile extends BaseMediaTile {
-    constructor(options) {
-        super(options);
+    constructor(entry, options) {
+        super(entry, options);
         this._lightboxUrl = this.urlCreator.urlForSegments([
             // ensure the right room is active if in grid view
             this.navigation.segment("room", this._room.id),
diff --git a/src/domain/session/room/timeline/tiles/RoomMemberTile.js b/src/domain/session/room/timeline/tiles/RoomMemberTile.js
index ce41f031..ca9cd9b7 100644
--- a/src/domain/session/room/timeline/tiles/RoomMemberTile.js
+++ b/src/domain/session/room/timeline/tiles/RoomMemberTile.js
@@ -66,23 +66,25 @@ export class RoomMemberTile extends SimpleTile {
 export function tests() {
     return {
         "user removes display name": (assert) => {
-            const tile = new RoomMemberTile({
-                entry: {
+            const tile = new RoomMemberTile(
+                {
                     prevContent: {displayname: "foo", membership: "join"},
                     content: {membership: "join"},
                     stateKey: "foo@bar.com",
                 },
-            });
+                {}
+            );
             assert.strictEqual(tile.announcement, "foo@bar.com removed their name (foo)");
         },
         "user without display name sets a new display name": (assert) => {
-            const tile = new RoomMemberTile({
-                entry: {
+            const tile = new RoomMemberTile(
+                {
                     prevContent: {membership: "join"},
                     content: {displayname: "foo", membership: "join" },
                     stateKey: "foo@bar.com",
                 },
-            });
+                {}
+            );
             assert.strictEqual(tile.announcement, "foo@bar.com changed their name to foo");
         },
     };
diff --git a/src/domain/session/room/timeline/tiles/SimpleTile.js b/src/domain/session/room/timeline/tiles/SimpleTile.js
index d70a0a37..cf954ac8 100644
--- a/src/domain/session/room/timeline/tiles/SimpleTile.js
+++ b/src/domain/session/room/timeline/tiles/SimpleTile.js
@@ -19,9 +19,9 @@ import {ViewModel} from "../../../../ViewModel";
 import {SendStatus} from "../../../../../matrix/room/sending/PendingEvent.js";
 
 export class SimpleTile extends ViewModel {
-    constructor(options) {
+    constructor(entry, options) {
         super(options);
-        this._entry = options.entry;
+        this._entry = entry;
     }
     // view model props for all subclasses
     // hmmm, could also do instanceof ... ?
diff --git a/src/domain/session/room/timeline/tiles/index.ts b/src/domain/session/room/timeline/tiles/index.ts
new file mode 100644
index 00000000..c41f90a6
--- /dev/null
+++ b/src/domain/session/room/timeline/tiles/index.ts
@@ -0,0 +1,105 @@
+/*
+Copyright 2020 Bruno Windels <bruno@windels.cloud>
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import {GapTile} from "./GapTile.js";
+import {TextTile} from "./TextTile.js";
+import {RedactedTile} from "./RedactedTile.js";
+import {ImageTile} from "./ImageTile.js";
+import {VideoTile} from "./VideoTile.js";
+import {FileTile} from "./FileTile.js";
+import {LocationTile} from "./LocationTile.js";
+import {RoomNameTile} from "./RoomNameTile.js";
+import {RoomMemberTile} from "./RoomMemberTile.js";
+import {EncryptedEventTile} from "./EncryptedEventTile.js";
+import {EncryptionEnabledTile} from "./EncryptionEnabledTile.js";
+import {MissingAttachmentTile} from "./MissingAttachmentTile.js";
+import {CallTile} from "./CallTile.js";
+
+import type {SimpleTile} from "./SimpleTile.js";
+import type {Room} from "../../../../../matrix/room/Room";
+import type {Session} from "../../../../../matrix/Session";
+import type {Timeline} from "../../../../../matrix/room/timeline/Timeline";
+import type {FragmentBoundaryEntry} from "../../../../../matrix/room/timeline/entries/FragmentBoundaryEntry";
+import type {EventEntry} from "../../../../../matrix/room/timeline/entries/EventEntry";
+import type {PendingEventEntry} from "../../../../../matrix/room/timeline/entries/PendingEventEntry";
+import type {Options as ViewModelOptions} from "../../../../ViewModel";
+
+export type TimelineEntry = FragmentBoundaryEntry | EventEntry | PendingEventEntry;
+export type TileClassForEntryFn = (entry: TimelineEntry) => TileConstructor | undefined;
+export type Options = ViewModelOptions & {
+    session: Session,
+    room: Room,
+    timeline: Timeline
+    tileClassForEntry: TileClassForEntryFn;
+};
+export type TileConstructor = new (entry: TimelineEntry, options: Options) => SimpleTile;
+
+export function tileClassForEntry(entry: TimelineEntry): TileConstructor | undefined {
+    if (entry.isGap) {
+        return GapTile;
+    } else if (entry.isPending && entry.pendingEvent.isMissingAttachments) {
+        return MissingAttachmentTile;
+    } else if (entry.eventType) {
+        switch (entry.eventType) {
+            case "m.room.message": {
+                if (entry.isRedacted) {
+                    return RedactedTile;
+                }
+                const content = entry.content;
+                const msgtype = content && content.msgtype;
+                switch (msgtype) {
+                    case "m.text":
+                    case "m.notice":
+                    case "m.emote":
+                        return TextTile;
+                    case "m.image":
+                        return ImageTile;
+                    case "m.video":
+                        return VideoTile;
+                    case "m.file":
+                        return FileTile;
+                    case "m.location":
+                        return LocationTile;
+                    default:
+                        // unknown msgtype not rendered
+                        return undefined;
+                }
+            }
+            case "m.room.name":
+                return RoomNameTile;
+            case "m.room.member":
+                return RoomMemberTile;
+            case "m.room.encrypted":
+                if (entry.isRedacted) {
+                    return RedactedTile;
+                }
+                return EncryptedEventTile;
+            case "m.room.encryption":
+                return EncryptionEnabledTile;
+            case "org.matrix.msc3401.call": {
+                // if prevContent is present, it's an update to a call event, which we don't render
+                // as the original event is updated through the call object which receive state event updates
+                if (entry.stateKey && !entry.prevContent) {
+                    return CallTile;
+                }
+                return undefined;
+            }
+            default:
+                // unknown type not rendered
+                return undefined;
+        }
+    }
+}
diff --git a/src/domain/session/room/timeline/tilesCreator.js b/src/domain/session/room/timeline/tilesCreator.js
deleted file mode 100644
index ad562df0..00000000
--- a/src/domain/session/room/timeline/tilesCreator.js
+++ /dev/null
@@ -1,86 +0,0 @@
-/*
-Copyright 2020 Bruno Windels <bruno@windels.cloud>
-
-Licensed under the Apache License, Version 2.0 (the "License");
-you may not use this file except in compliance with the License.
-You may obtain a copy of the License at
-
-    http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.
-*/
-
-import {GapTile} from "./tiles/GapTile.js";
-import {TextTile} from "./tiles/TextTile.js";
-import {RedactedTile} from "./tiles/RedactedTile.js";
-import {ImageTile} from "./tiles/ImageTile.js";
-import {VideoTile} from "./tiles/VideoTile.js";
-import {FileTile} from "./tiles/FileTile.js";
-import {LocationTile} from "./tiles/LocationTile.js";
-import {RoomNameTile} from "./tiles/RoomNameTile.js";
-import {RoomMemberTile} from "./tiles/RoomMemberTile.js";
-import {EncryptedEventTile} from "./tiles/EncryptedEventTile.js";
-import {EncryptionEnabledTile} from "./tiles/EncryptionEnabledTile.js";
-import {MissingAttachmentTile} from "./tiles/MissingAttachmentTile.js";
-import {CallTile} from "./tiles/CallTile.js";
-
-export function tilesCreator(baseOptions) {
-    const tilesCreator = function tilesCreator(entry, emitUpdate) {
-        const options = Object.assign({entry, emitUpdate, tilesCreator}, baseOptions);
-        if (entry.isGap) {
-            return new GapTile(options);
-        } else if (entry.isPending && entry.pendingEvent.isMissingAttachments) {
-            return new MissingAttachmentTile(options);
-        } else if (entry.eventType) {
-            switch (entry.eventType) {
-                case "m.room.message": {
-                    if (entry.isRedacted) {
-                        return new RedactedTile(options);
-                    }
-                    const content = entry.content;
-                    const msgtype = content && content.msgtype;
-                    switch (msgtype) {
-                        case "m.text":
-                        case "m.notice":
-                        case "m.emote":
-                            return new TextTile(options);
-                        case "m.image":
-                            return new ImageTile(options);
-                        case "m.video":
-                            return new VideoTile(options);
-                        case "m.file":
-                            return new FileTile(options);
-                        case "m.location":
-                            return new LocationTile(options);
-                        default:
-                            // unknown msgtype not rendered
-                            return null;
-                    }
-                }
-                case "m.room.name":
-                    return new RoomNameTile(options);
-                case "m.room.member":
-                    return new RoomMemberTile(options);
-                case "m.room.encrypted":
-                    if (entry.isRedacted) {
-                        return new RedactedTile(options);
-                    }
-                    return new EncryptedEventTile(options);
-                case "m.room.encryption":
-                    return new EncryptionEnabledTile(options);
-                case "org.matrix.msc3401.call":
-                    // if prevContent is present, it's an update to a call event, which we don't render
-                    // as the original event is updated through the call object which receive state event updates
-                    return entry.stateKey && !entry.prevContent ? new CallTile(options) : null;
-                default:
-                    // unknown type not rendered
-                    return null;
-            }
-        }
-    };
-    return tilesCreator;
-}
diff --git a/src/lib.ts b/src/lib.ts
index cb939949..e2da5e16 100644
--- a/src/lib.ts
+++ b/src/lib.ts
@@ -26,7 +26,41 @@ export {SessionView} from "./platform/web/ui/session/SessionView.js";
 export {RoomViewModel} from "./domain/session/room/RoomViewModel.js";
 export {RoomView} from "./platform/web/ui/session/room/RoomView.js";
 export {TimelineViewModel} from "./domain/session/room/timeline/TimelineViewModel.js";
+export {tileClassForEntry} from "./domain/session/room/timeline/tiles/index";
+export type {TimelineEntry, TileClassForEntryFn, Options, TileConstructor} from "./domain/session/room/timeline/tiles/index";
+// export timeline tile view models
+export {GapTile} from "./domain/session/room/timeline/tiles/GapTile.js";
+export {TextTile} from "./domain/session/room/timeline/tiles/TextTile.js";
+export {RedactedTile} from "./domain/session/room/timeline/tiles/RedactedTile.js";
+export {ImageTile} from "./domain/session/room/timeline/tiles/ImageTile.js";
+export {VideoTile} from "./domain/session/room/timeline/tiles/VideoTile.js";
+export {FileTile} from "./domain/session/room/timeline/tiles/FileTile.js";
+export {LocationTile} from "./domain/session/room/timeline/tiles/LocationTile.js";
+export {RoomNameTile} from "./domain/session/room/timeline/tiles/RoomNameTile.js";
+export {RoomMemberTile} from "./domain/session/room/timeline/tiles/RoomMemberTile.js";
+export {EncryptedEventTile} from "./domain/session/room/timeline/tiles/EncryptedEventTile.js";
+export {EncryptionEnabledTile} from "./domain/session/room/timeline/tiles/EncryptionEnabledTile.js";
+export {MissingAttachmentTile} from "./domain/session/room/timeline/tiles/MissingAttachmentTile.js";
+export {SimpleTile} from "./domain/session/room/timeline/tiles/SimpleTile.js";
+
 export {TimelineView} from "./platform/web/ui/session/room/TimelineView";
+export {viewClassForTile} from "./platform/web/ui/session/room/common";
+export type {TileViewConstructor, ViewClassForEntryFn} from "./platform/web/ui/session/room/TimelineView";
+// export timeline tile views
+export {AnnouncementView} from "./platform/web/ui/session/room/timeline/AnnouncementView.js";
+export {BaseMediaView} from "./platform/web/ui/session/room/timeline/BaseMediaView.js";
+export {BaseMessageView} from "./platform/web/ui/session/room/timeline/BaseMessageView.js";
+export {FileView} from "./platform/web/ui/session/room/timeline/FileView.js";
+export {GapView} from "./platform/web/ui/session/room/timeline/GapView.js";
+export {ImageView} from "./platform/web/ui/session/room/timeline/ImageView.js";
+export {LocationView} from "./platform/web/ui/session/room/timeline/LocationView.js";
+export {MissingAttachmentView} from "./platform/web/ui/session/room/timeline/MissingAttachmentView.js";
+export {ReactionsView} from "./platform/web/ui/session/room/timeline/ReactionsView.js";
+export {RedactedView} from "./platform/web/ui/session/room/timeline/RedactedView.js";
+export {ReplyPreviewView} from "./platform/web/ui/session/room/timeline/ReplyPreviewView.js";
+export {TextMessageView} from "./platform/web/ui/session/room/timeline/TextMessageView.js";
+export {VideoView} from "./platform/web/ui/session/room/timeline/VideoView.js";
+
 export {Navigation} from "./domain/navigation/Navigation.js";
 export {ComposerViewModel} from "./domain/session/room/ComposerViewModel.js";
 export {MessageComposer} from "./platform/web/ui/session/room/MessageComposer.js";
diff --git a/src/platform/web/ui/session/RoomGridView.js b/src/platform/web/ui/session/RoomGridView.js
index 79fc3d21..65289bea 100644
--- a/src/platform/web/ui/session/RoomGridView.js
+++ b/src/platform/web/ui/session/RoomGridView.js
@@ -21,6 +21,11 @@ import {TemplateView} from "../general/TemplateView";
 import {StaticView} from "../general/StaticView.js";
 
 export class RoomGridView extends TemplateView {
+    constructor(vm, viewClassForTile) {
+        super(vm);
+        this._viewClassForTile = viewClassForTile;
+    }
+
     render(t, vm) {
         const children = [];
         for (let i = 0; i < (vm.height * vm.width); i+=1) {
@@ -39,7 +44,7 @@ export class RoomGridView extends TemplateView {
                     } else if (roomVM.kind === "invite") {
                         return new InviteView(roomVM);
                     } else {
-                        return new RoomView(roomVM);
+                        return new RoomView(roomVM, this._viewClassForTile);
                     }
                 } else {
                     return new StaticView(t => t.div({className: "room-placeholder"}, [
diff --git a/src/platform/web/ui/session/SessionView.js b/src/platform/web/ui/session/SessionView.js
index e7cc406a..ef63b29b 100644
--- a/src/platform/web/ui/session/SessionView.js
+++ b/src/platform/web/ui/session/SessionView.js
@@ -28,6 +28,7 @@ import {RoomGridView} from "./RoomGridView.js";
 import {SettingsView} from "./settings/SettingsView.js";
 import {CreateRoomView} from "./CreateRoomView.js";
 import {RightPanelView} from "./rightpanel/RightPanelView.js";
+import {viewClassForTile} from "./room/common";
 
 export class SessionView extends TemplateView {
     render(t, vm) {
@@ -42,7 +43,7 @@ export class SessionView extends TemplateView {
             t.view(new LeftPanelView(vm.leftPanelViewModel)),
             t.mapView(vm => vm.activeMiddleViewModel, () => {
                 if (vm.roomGridViewModel) {
-                    return new RoomGridView(vm.roomGridViewModel);
+                    return new RoomGridView(vm.roomGridViewModel, viewClassForTile);
                 } else if (vm.settingsViewModel) {
                     return new SettingsView(vm.settingsViewModel);
                 } else if (vm.createRoomViewModel) {
@@ -51,7 +52,7 @@ export class SessionView extends TemplateView {
                     if (vm.currentRoomViewModel.kind === "invite") {
                         return new InviteView(vm.currentRoomViewModel);
                     } else if (vm.currentRoomViewModel.kind === "room") {
-                        return new RoomView(vm.currentRoomViewModel);
+                        return new RoomView(vm.currentRoomViewModel, viewClassForTile);
                     } else if (vm.currentRoomViewModel.kind === "roomBeingCreated") {
                         return new RoomBeingCreatedView(vm.currentRoomViewModel);
                     } else {
diff --git a/src/platform/web/ui/session/room/MessageComposer.js b/src/platform/web/ui/session/room/MessageComposer.js
index 9c67fa9f..6ce8148f 100644
--- a/src/platform/web/ui/session/room/MessageComposer.js
+++ b/src/platform/web/ui/session/room/MessageComposer.js
@@ -17,11 +17,11 @@ limitations under the License.
 import {TemplateView} from "../../general/TemplateView";
 import {Popup} from "../../general/Popup.js";
 import {Menu} from "../../general/Menu.js";
-import {viewClassForEntry} from "./common"
 
 export class MessageComposer extends TemplateView {
-    constructor(viewModel) {
+    constructor(viewModel, viewClassForTile) {
         super(viewModel);
+        this._viewClassForTile = viewClassForTile;
         this._input = null;
         this._attachmentPopup = null;
         this._focusInput = null;
@@ -45,8 +45,8 @@ export class MessageComposer extends TemplateView {
         this._focusInput = () => this._input.focus();
         this.value.on("focus", this._focusInput);
         const replyPreview = t.map(vm => vm.replyViewModel, (rvm, t) => {
-            const View = rvm && viewClassForEntry(rvm);
-            if (!View) { return null; }
+            const TileView = rvm && this._viewClassForTile(rvm);
+            if (!TileView) { return null; }
             return t.div({
                     className: "MessageComposer_replyPreview"
                 }, [
@@ -55,8 +55,8 @@ export class MessageComposer extends TemplateView {
                         className: "cancel",
                         onClick: () => this._clearReplyingTo()
                     }, "Close"),
-                t.view(new View(rvm, { interactive: false }, "div"))
-                ])
+                t.view(new TileView(rvm, this._viewClassForTile, { interactive: false }, "div"))
+            ]);
         });
         const input = t.div({className: "MessageComposer_input"}, [
             this._input,
diff --git a/src/platform/web/ui/session/room/RoomView.js b/src/platform/web/ui/session/room/RoomView.js
index 2936adf3..4f9e40d9 100644
--- a/src/platform/web/ui/session/room/RoomView.js
+++ b/src/platform/web/ui/session/room/RoomView.js
@@ -26,15 +26,16 @@ import {AvatarView} from "../../AvatarView.js";
 import {CallView} from "./CallView";
 
 export class RoomView extends TemplateView {
-    constructor(options) {
-        super(options);
+    constructor(vm, viewClassForTile) {
+        super(vm);
+        this._viewClassForTile = viewClassForTile;
         this._optionsPopup = null;
     }
 
     render(t, vm) {
         let bottomView;
         if (vm.composerViewModel.kind === "composer") {
-            bottomView = new MessageComposer(vm.composerViewModel);
+            bottomView = new MessageComposer(vm.composerViewModel, this._viewClassForTile);
         } else if (vm.composerViewModel.kind === "archived") {
             bottomView = new RoomArchivedView(vm.composerViewModel);
         }
@@ -56,7 +57,7 @@ export class RoomView extends TemplateView {
                 t.mapView(vm => vm.callViewModel, callViewModel => callViewModel ? new CallView(callViewModel) : null),
                 t.mapView(vm => vm.timelineViewModel, timelineViewModel => {
                     return timelineViewModel ?
-                        new TimelineView(timelineViewModel) :
+                        new TimelineView(timelineViewModel, this._viewClassForTile) :
                         new TimelineLoadingView(vm);    // vm is just needed for i18n
                 }),
                 t.view(bottomView),
diff --git a/src/platform/web/ui/session/room/TimelineView.ts b/src/platform/web/ui/session/room/TimelineView.ts
index 936b8c7c..5a04991f 100644
--- a/src/platform/web/ui/session/room/TimelineView.ts
+++ b/src/platform/web/ui/session/room/TimelineView.ts
@@ -14,9 +14,8 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import type {TileView} from "./common";
-import {viewClassForEntry} from "./common";
 import {ListView} from "../../general/ListView";
+import type {IView} from "../../general/types";
 import {TemplateView, Builder} from "../../general/TemplateView";
 import {IObservableValue} from "../../general/BaseUpdateView";
 import {MissingAttachmentView} from "./timeline/MissingAttachmentView.js";
@@ -25,6 +24,17 @@ import {RedactedView} from "./timeline/RedactedView.js";
 import {SimpleTile} from "../../../../../domain/session/room/timeline/tiles/SimpleTile.js";
 import {BaseObservableList as ObservableList} from "../../../../../observable/list/BaseObservableList";
 
+export interface TileView extends IView {
+    readonly value: SimpleTile;
+    onClick(event: UIEvent);
+} 
+export type TileViewConstructor = new (
+    tile: SimpleTile,
+    viewClassForTile: ViewClassForEntryFn,
+    renderFlags?: { reply?: boolean, interactive?: boolean }
+) => TileView;
+export type ViewClassForEntryFn = (tile: SimpleTile) => TileViewConstructor;
+
 //import {TimelineViewModel} from "../../../../../domain/session/room/timeline/TimelineViewModel.js";
 export interface TimelineViewModel extends IObservableValue {
     showJumpDown: boolean;
@@ -55,13 +65,17 @@ export class TimelineView extends TemplateView<TimelineViewModel> {
     private tilesView?: TilesListView;
     private resizeObserver?: ResizeObserver;
 
+    constructor(vm: TimelineViewModel, private readonly viewClassForTile: ViewClassForEntryFn) {
+        super(vm);
+    }
+
     render(t: Builder<TimelineViewModel>, vm: TimelineViewModel) {
         // assume this view will be mounted in the parent DOM straight away
         requestAnimationFrame(() => {
             // do initial scroll positioning
             this.restoreScrollPosition();
         });
-        this.tilesView = new TilesListView(vm.tiles, () => this.restoreScrollPosition());
+        this.tilesView = new TilesListView(vm.tiles, () => this.restoreScrollPosition(), this.viewClassForTile);
         const root = t.div({className: "Timeline"}, [
             t.div({
                 className: "Timeline_scroller bottom-aligned-scroll",
@@ -174,16 +188,13 @@ class TilesListView extends ListView<SimpleTile, TileView> {
 
     private onChanged: () => void;
 
-    constructor(tiles: ObservableList<SimpleTile>, onChanged: () => void) {
-        const options = {
+    constructor(tiles: ObservableList<SimpleTile>, onChanged: () => void, private readonly viewClassForTile: ViewClassForEntryFn) {
+        super({
             list: tiles,
             onItemClick: (tileView, evt) => tileView.onClick(evt),
-        };
-        super(options, entry => {
-            const View = viewClassForEntry(entry);
-            if (View) {
-                return new View(entry);
-            }
+        }, tile => {
+            const TileView = viewClassForTile(tile);
+            return new TileView(tile, viewClassForTile);
         });
         this.onChanged = onChanged;
     }
@@ -195,7 +206,7 @@ class TilesListView extends ListView<SimpleTile, TileView> {
 
     onUpdate(index: number, value: SimpleTile, param: any) {
         if (param === "shape") {
-            const ExpectedClass = viewClassForEntry(value);
+            const ExpectedClass = this.viewClassForTile(value);
             const child = this.getChildInstanceByIndex(index);
             if (!ExpectedClass || !(child instanceof ExpectedClass)) {
                 // shape was updated, so we need to recreate the tile view,
diff --git a/src/platform/web/ui/session/room/common.ts b/src/platform/web/ui/session/room/common.ts
index 28543bcf..74007cee 100644
--- a/src/platform/web/ui/session/room/common.ts
+++ b/src/platform/web/ui/session/room/common.ts
@@ -25,14 +25,10 @@ import {RedactedView} from "./timeline/RedactedView.js";
 import {SimpleTile} from "../../../../../domain/session/room/timeline/tiles/SimpleTile.js";
 import {GapView} from "./timeline/GapView.js";
 import {CallTileView} from "./timeline/CallTileView";
+import type {TileViewConstructor, ViewClassForEntryFn} from "./TimelineView";
 
-export type TileView = GapView | AnnouncementView | TextMessageView |
-    ImageView | VideoView | FileView | LocationView | MissingAttachmentView | RedactedView;
-
-// TODO: this is what works for a ctor but doesn't actually check we constrain the returned ctors to the types above
-type TileViewConstructor = (this: TileView, SimpleTile) => void;
-export function viewClassForEntry(entry: SimpleTile): TileViewConstructor | undefined {
-    switch (entry.shape) {
+export function viewClassForTile(vm: SimpleTile): TileViewConstructor {
+    switch (vm.shape) {
         case "gap":
             return GapView;
         case "announcement":
@@ -53,6 +49,8 @@ export function viewClassForEntry(entry: SimpleTile): TileViewConstructor | unde
         case "redacted":
             return RedactedView;
         case "call":
-            return CallTileView as any as TileViewConstructor;
+            return CallTileView;
+        default:
+            throw new Error(`Tiles of shape "${vm.shape}" are not supported, check the tileClassForEntry function in the view model`);
     }
 }
diff --git a/src/platform/web/ui/session/room/timeline/AnnouncementView.js b/src/platform/web/ui/session/room/timeline/AnnouncementView.js
index 268bf0fa..5ae92daa 100644
--- a/src/platform/web/ui/session/room/timeline/AnnouncementView.js
+++ b/src/platform/web/ui/session/room/timeline/AnnouncementView.js
@@ -17,6 +17,11 @@ limitations under the License.
 import {TemplateView} from "../../../general/TemplateView";
 
 export class AnnouncementView extends TemplateView {
+    // ignore other arguments
+    constructor(vm) {
+        super(vm);
+    }
+
     render(t) {
         return t.li({className: "AnnouncementView"}, t.div(vm => vm.announcement));
     }
diff --git a/src/platform/web/ui/session/room/timeline/BaseMessageView.js b/src/platform/web/ui/session/room/timeline/BaseMessageView.js
index 7356cd2b..74b96ecf 100644
--- a/src/platform/web/ui/session/room/timeline/BaseMessageView.js
+++ b/src/platform/web/ui/session/room/timeline/BaseMessageView.js
@@ -24,10 +24,11 @@ import {Menu} from "../../../general/Menu.js";
 import {ReactionsView} from "./ReactionsView.js";
 
 export class BaseMessageView extends TemplateView {
-    constructor(value, renderFlags, tagName = "li") {
+    constructor(value, viewClassForTile, renderFlags, tagName = "li") {
         super(value);
         this._menuPopup = null;
         this._tagName = tagName;
+        this._viewClassForTile = viewClassForTile;
         // TODO An enum could be nice to make code easier to read at call sites.
         this._renderFlags = renderFlags;
     }
diff --git a/src/platform/web/ui/session/room/timeline/GapView.js b/src/platform/web/ui/session/room/timeline/GapView.js
index 2d3bd6e8..db6cda59 100644
--- a/src/platform/web/ui/session/room/timeline/GapView.js
+++ b/src/platform/web/ui/session/room/timeline/GapView.js
@@ -18,6 +18,11 @@ import {TemplateView} from "../../../general/TemplateView";
 import {spinner} from "../../../common.js";
 
 export class GapView extends TemplateView {
+    // ignore other argument
+    constructor(vm) {
+        super(vm);
+    }
+
     render(t) {
         const className = {
             GapView: true,
diff --git a/src/platform/web/ui/session/room/timeline/ReplyPreviewView.js b/src/platform/web/ui/session/room/timeline/ReplyPreviewView.js
index 3c52fc71..219e4357 100644
--- a/src/platform/web/ui/session/room/timeline/ReplyPreviewView.js
+++ b/src/platform/web/ui/session/room/timeline/ReplyPreviewView.js
@@ -16,15 +16,18 @@ limitations under the License.
 
 import {renderStaticAvatar} from "../../../avatar";
 import {TemplateView} from "../../../general/TemplateView";
-import {viewClassForEntry} from "../common";
 
 export class ReplyPreviewView extends TemplateView {
+    constructor(vm, viewClassForTile) {
+        super(vm);
+        this._viewClassForTile = viewClassForTile;
+    }
     render(t, vm) {
-        const viewClass = viewClassForEntry(vm);
-        if (!viewClass) {
+        const TileView = this._viewClassForTile(vm);
+        if (!TileView) {
             throw new Error(`Shape ${vm.shape} is unrecognized.`)
         }
-        const view = new viewClass(vm, { reply: true, interactive: false });
+        const view = new TileView(vm, this._viewClassForTile, { reply: true, interactive: false });
         return t.div(
             { className: "ReplyPreviewView" },
             t.blockquote([
diff --git a/src/platform/web/ui/session/room/timeline/TextMessageView.js b/src/platform/web/ui/session/room/timeline/TextMessageView.js
index c0c0cfb0..8d6cb4dc 100644
--- a/src/platform/web/ui/session/room/timeline/TextMessageView.js
+++ b/src/platform/web/ui/session/room/timeline/TextMessageView.js
@@ -35,7 +35,7 @@ export class TextMessageView extends BaseMessageView {
                 return new ReplyPreviewError();
             }
             else if (replyTile) {
-                return new ReplyPreviewView(replyTile);
+                return new ReplyPreviewView(replyTile, this._viewClassForTile);
             }
             else {
                 return null;