diff --git a/src/ui/web/ListView.js b/src/ui/web/ListView.js
index 2fb377d4..f12651a3 100644
--- a/src/ui/web/ListView.js
+++ b/src/ui/web/ListView.js
@@ -1,4 +1,4 @@
-import * as html from "./html.js";
+import {tag} from "./html.js";
 
 class UIView {
     mount() {}
@@ -47,7 +47,7 @@ export default class ListView {
     }
 
     mount() {
-        this._root = html.ul({className: "ListView"});
+        this._root = tag.ul({className: "ListView"});
         this._loadList();
         if (this._onItemClick) {
             this._root.addEventListener("click", this._onClick);
diff --git a/src/ui/web/RoomTile.js b/src/ui/web/RoomTile.js
index 4beb6f1a..a68049ab 100644
--- a/src/ui/web/RoomTile.js
+++ b/src/ui/web/RoomTile.js
@@ -1,29 +1,12 @@
-import { li } from "./html.js";
+import TemplateView from "./TemplateView.js";
 
-export default class RoomTile {
-    constructor(viewModel) {
-        this._viewModel = viewModel;
-        this._root = null;
-    }
-
-    mount() {
-        this._root = li(null, this._viewModel.name);
-        return this._root;
-    }
-
-    unmount() {
-    }
-
-    update() {
-        // no data-binding yet
-        this._root.innerText = this._viewModel.name;
+export default class RoomTile extends TemplateView {
+    render(t) {
+        return t.li(vm => vm.name);
     }
 
+    // called from ListView
     clicked() {
-        this._viewModel.open();
-    }
-
-    root() {
-        return this._root;
+        this.viewModel.open();
     }
 }
diff --git a/src/ui/web/RoomView.js b/src/ui/web/RoomView.js
index d26cf5df..35523c9f 100644
--- a/src/ui/web/RoomView.js
+++ b/src/ui/web/RoomView.js
@@ -1,6 +1,7 @@
 import TimelineTile from "./TimelineTile.js";
 import ListView from "./ListView.js";
-import * as html from "./html.js";
+import {tag} from "./html.js";
+import GapView from "./timeline/GapView.js";
 
 export default class RoomView {
     constructor(viewModel) {
@@ -13,13 +14,15 @@ export default class RoomView {
 
     mount() {
         this._viewModel.on("change", this._onViewModelUpdate);
-        this._nameLabel = html.h2(null, this._viewModel.name);
-        this._errorLabel = html.div({className: "RoomView_error"});
+        this._nameLabel = tag.h2(null, this._viewModel.name);
+        this._errorLabel = tag.div({className: "RoomView_error"});
 
-        this._timelineList = new ListView({}, entry => new TimelineTile(entry));
+        this._timelineList = new ListView({}, entry => {
+            return entry.shape === "gap" ? new GapView(entry) : new TimelineTile(entry);
+        });
         this._timelineList.mount();
 
-        this._root = html.div({className: "RoomView"}, [
+        this._root = tag.div({className: "RoomView"}, [
             this._nameLabel,
             this._errorLabel,
             this._timelineList.root()
diff --git a/src/ui/web/SessionView.js b/src/ui/web/SessionView.js
index 98373a86..ba92f80b 100644
--- a/src/ui/web/SessionView.js
+++ b/src/ui/web/SessionView.js
@@ -1,7 +1,7 @@
 import ListView from "./ListView.js";
 import RoomTile from "./RoomTile.js";
 import RoomView from "./RoomView.js";
-import { div } from "./html.js";
+import {tag} from "./html.js";
 
 export default class SessionView {
     constructor(viewModel) {
@@ -19,7 +19,7 @@ export default class SessionView {
     mount() {
         this._viewModel.on("change", this._onViewModelChange);
 
-        this._root = div({className: "SessionView"});
+        this._root = tag.div({className: "SessionView"});
         this._roomList = new ListView(
             {
                 list: this._viewModel.roomList,
diff --git a/src/ui/web/Template.js b/src/ui/web/Template.js
new file mode 100644
index 00000000..de47a6f0
--- /dev/null
+++ b/src/ui/web/Template.js
@@ -0,0 +1,231 @@
+import { setAttribute, text, TAG_NAMES } from "./html.js";
+
+
+function classNames(obj, value) {
+    return Object.entries(obj).reduce((cn, [name, enabled]) => {
+        if (typeof enabled === "function") {
+            enabled = enabled(value);
+        }
+        if (enabled) {
+            return (cn.length ? " " : "") + name;
+        } else {
+            return cn;
+        }
+    }, "");
+}
+/**
+    Bindable template. Renders once, and allows bindings for given nodes. If you need
+    to change the structure on a condition, use a subtemplate (if)
+
+    supports
+        - event handlers (attribute fn value with name that starts with on)
+        - one way binding of attributes (other attribute fn value)
+        - one way binding of text values (child fn value)
+        - refs to get dom nodes
+        - className binding returning object with className => enabled map
+    missing:
+        - create views
+*/
+export default class Template {
+    constructor(value, render) {
+        this._value = value;
+        this._eventListeners = null;
+        this._bindings = null;
+        this._subTemplates = null;
+        this._root = render(this, this._value);
+        this._attach();
+    }
+
+    root() {
+        return this._root;
+    }
+
+    update(value) {
+        this._value = value;
+        if (this._bindings) {
+            for (const binding of this._bindings) {
+                binding();
+            }
+        }
+        if (this._subTemplates) {
+            for (const sub of this._subTemplates) {
+                sub.update(value);
+            }
+        }
+    }
+
+    dispose() {
+        if (this._eventListeners) {
+            for (let {node, name, fn} of this._eventListeners) {
+                node.removeEventListener(name, fn);
+            }
+        }
+        if (this._subTemplates) {
+            for (const sub of this._subTemplates) {
+                sub.dispose();
+            }
+        }
+    }
+
+    _attach() {
+        if (this._eventListeners) {
+            for (let {node, name, fn} of this._eventListeners) {
+                node.addEventListener(name, fn);
+            }
+        }
+    }
+
+    _addEventListener(node, name, fn) {
+        if (!this._eventListeners) {
+            this._eventListeners = [];
+        }
+        this._eventListeners.push({node, name, fn});
+    }
+
+    _addBinding(bindingFn) {
+        if (!this._bindings) {
+            this._bindings = [];
+        }
+        this._bindings.push(bindingFn);
+    }
+
+    _addSubTemplate(t) {
+        if (!this._subTemplates) {
+            this._subTemplates = [];
+        }
+        this._subTemplates.push(t);
+    }
+
+    _addAttributeBinding(node, name, fn) {
+        let prevValue = undefined;
+        const binding = () => {
+            const newValue = fn(this._value);
+            if (prevValue !== newValue) {
+                prevValue = newValue;
+                setAttribute(node, name, newValue);
+            }
+        };
+        this._addBinding(binding);
+        binding();
+    }
+
+    _addClassNamesBinding(node, obj) {
+        this._addAttributeBinding(node, "className", value => classNames(obj, value));
+    }
+
+    _addTextBinding(fn) {
+        const initialValue = fn(this._value);
+        const node = text(initialValue);
+        let prevValue = initialValue;
+        const binding = () => {
+            const newValue = fn(this._value);
+            if (prevValue !== newValue) {
+                prevValue = newValue;
+                node.textContent = newValue+"";
+            }
+        };
+
+        this._addBinding(binding);
+        return node;
+    }
+
+    el(name, attributes, children) {
+        if (attributes) {
+            // valid attributes is only object that is not a DOM node
+            // anything else (string, fn, array, dom node) is presumed
+            // to be children with no attributes passed
+            if (typeof attributes !== "object" || !!attributes.nodeType || Array.isArray(attributes)) {
+                children = attributes;
+                attributes = null;
+            }
+        }
+
+        const node = document.createElement(name);
+        
+        if (attributes) {
+            this._setNodeAttributes(node, attributes);
+        }
+        if (children) {
+            this._setNodeChildren(node, children);
+        }
+
+        return node;
+    }
+
+    _setNodeAttributes(node, attributes) {
+        for(let [key, value] of Object.entries(attributes)) {
+            const isFn = typeof value === "function";
+            // binding for className as object of className => enabled
+            if (key === "className" && typeof value === "object" && value !== null) {
+                this._addClassNamesBinding(node, value);
+            } else if (key.startsWith("on") && key.length > 2 && isFn) {
+                const eventName = key.substr(2, 1).toLowerCase() + key.substr(3);
+                const handler = value;
+                this._addEventListener(node, eventName, handler);
+            } else if (isFn) {
+                this._addAttributeBinding(node, key, value);
+            } else {
+                setAttribute(node, key, value);
+            }
+        }
+    }
+
+    _setNodeChildren(node, children) {
+        if (!Array.isArray(children)) {
+            children = [children];
+        }
+        for (let child of children) {
+            if (typeof child === "function") {
+                child = this._addTextBinding(child);
+            } else if (!child.nodeType) {
+                // not a DOM node, turn into text
+                child = text(child);
+            }
+            node.appendChild(child);
+        }
+    }
+    
+    _addReplaceNodeBinding(fn, renderNode) {
+        let prevValue = fn(this._value);
+        let node = renderNode(null);
+
+        const binding = () => {
+            const newValue = fn(this._value);
+            if (prevValue !== newValue) {
+                prevValue = newValue;
+                const newNode = renderNode(node);
+                if (node.parentElement) {
+                    node.parentElement.replaceChild(newNode, node);
+                }
+                node = newNode;
+            }
+        };
+        this._addBinding(binding);
+        return node;
+    }
+
+    // creates a conditional subtemplate
+    if(fn, render) {
+        const boolFn = value => !!fn(value);
+        return this._addReplaceNodeBinding(boolFn, (prevNode) => {
+            if (prevNode && prevNode.nodeType !== Node.COMMENT_NODE) {
+                const templateIdx = this._subTemplates.findIndex(t => t.root() === prevNode);
+                const [template] = this._subTemplates.splice(templateIdx, 1);
+                template.dispose();
+            }
+            if (boolFn(this._value)) {
+                const template = new Template(this._value, render);
+                this._addSubTemplate(template);
+                return template.root();
+            } else {
+                return document.createComment("if placeholder");
+            }
+        });
+    }
+}
+
+for (const tag of TAG_NAMES) {
+    Template.prototype[tag] = function(attributes, children) {
+        return this.el(tag, attributes, children);
+    };
+}
diff --git a/src/ui/web/TemplateView.js b/src/ui/web/TemplateView.js
new file mode 100644
index 00000000..96d1a500
--- /dev/null
+++ b/src/ui/web/TemplateView.js
@@ -0,0 +1,30 @@
+import Template from "./Template.js";
+
+export default class TemplateView {
+    constructor(value) {
+        this.viewModel = value;
+        this._template = null;
+    }
+
+    render() {
+        throw new Error("render not implemented");
+    }
+
+    mount() {
+        this._template = new Template(this.viewModel, (t, value) => this.render(t, value));
+        return this.root();
+    }
+
+    root() {
+        return this._template.root();
+    }
+
+    unmount() {
+        this._template.dispose();
+        this._template = null;
+    }
+
+    update(value) {
+        this._template.update(value);
+    }
+}
diff --git a/src/ui/web/TimelineTile.js b/src/ui/web/TimelineTile.js
index 0e583a37..8ee411d2 100644
--- a/src/ui/web/TimelineTile.js
+++ b/src/ui/web/TimelineTile.js
@@ -1,4 +1,4 @@
-import * as html from "./html.js";
+import {tag} from "./html.js";
 
 export default class TimelineTile {
     constructor(tileVM) {
@@ -24,19 +24,10 @@ export default class TimelineTile {
 function renderTile(tile) {
     switch (tile.shape) {
         case "message":
-            return html.li(null, [html.strong(null, tile.internalId+" "), tile.label]);
-        case "gap": {
-            const button = html.button(null, (tile.isUp ? "🠝" : "🠟") + " fill gap");
-            const handler = () => {
-                tile.fill();
-                button.removeEventListener("click", handler);
-            };
-            button.addEventListener("click", handler);
-            return html.li(null, [html.strong(null, tile.internalId+" "), button]);
-        }
+            return tag.li(null, [tag.strong(null, tile.internalId+" "), tile.label]);
         case "announcement":
-            return html.li(null, [html.strong(null, tile.internalId+" "), tile.label]);
+            return tag.li(null, [tag.strong(null, tile.internalId+" "), tile.label]);
         default:
-            return html.li(null, [html.strong(null, tile.internalId+" "), "unknown tile shape: " + tile.shape]);
+            return tag.li(null, [tag.strong(null, tile.internalId+" "), "unknown tile shape: " + tile.shape]);
     }
 }
diff --git a/src/ui/web/html.js b/src/ui/web/html.js
index ebf57091..604090f2 100644
--- a/src/ui/web/html.js
+++ b/src/ui/web/html.js
@@ -1,8 +1,17 @@
+// DOM helper functions
+
 export function setAttribute(el, name, value) {
     if (name === "className") {
         name = "class";
     }
-    el.setAttribute(name, value);
+    if (value === false) {
+        el.removeAttribute(name);
+    } else {
+        if (value === true) {
+            value = name;
+        }
+        el.setAttribute(name, value);
+    }
 }
 
 export function el(elementName, attrs, children) {
@@ -16,9 +25,8 @@ export function el(elementName, attrs, children) {
         if (!Array.isArray(children)) {
             children = [children];
         }
-        // TODO: use fragment here?
         for (let c of children) {
-            if (typeof c === "string") {
+            if (!c.nodeType) {
                 c = text(c);
             }
             e.appendChild(c);
@@ -31,24 +39,15 @@ export function text(str) {
     return document.createTextNode(str);
 }
 
-export function ol(... params)      { return el("ol", ... params); }
-export function ul(... params)      { return el("ul", ... params); }
-export function li(... params)      { return el("li", ... params); }
-export function div(... params)     { return el("div", ... params); }
-export function h1(... params)      { return el("h1", ... params); }
-export function h2(... params)      { return el("h2", ... params); }
-export function h3(... params)      { return el("h3", ... params); }
-export function h4(... params)      { return el("h4", ... params); }
-export function h5(... params)      { return el("h5", ... params); }
-export function h6(... params)      { return el("h6", ... params); }
-export function p(... params)       { return el("p", ... params); }
-export function strong(... params)  { return el("strong", ... params); }
-export function em(... params)      { return el("em", ... params); }
-export function span(... params)    { return el("span", ... params); }
-export function img(... params)     { return el("img", ... params); }
-export function section(... params) { return el("section", ... params); }
-export function main(... params)    { return el("main", ... params); }
-export function article(... params) { return el("article", ... params); }
-export function aside(... params)   { return el("aside", ... params); }
-export function pre(... params)   { return el("pre", ... params); }
-export function button(... params)   { return el("button", ... params); }
+export const TAG_NAMES = [
+    "ol", "ul", "li", "div", "h1", "h2", "h3", "h4", "h5", "h6",
+    "p", "strong", "em", "span", "img", "section", "main", "article", "aside",
+    "pre", "button"];
+
+export const tag = {};
+
+for (const tagName of TAG_NAMES) {
+    tag[tagName] = function(attributes, children) {
+        return el(tagName, attributes, children);
+    }
+}
diff --git a/src/ui/web/timeline/GapView.js b/src/ui/web/timeline/GapView.js
new file mode 100644
index 00000000..258cc167
--- /dev/null
+++ b/src/ui/web/timeline/GapView.js
@@ -0,0 +1,15 @@
+import TemplateView from "../TemplateView.js";
+
+export default class GapView extends TemplateView {
+    render(t, vm) {
+        const className = {
+            gap: true,
+            isLoading: vm => vm.isLoading
+        };
+        const label = (vm.isUp ? "🠝" : "🠟") + " fill gap"; //no binding
+        return t.li({className}, [
+            t.button({onClick: () => this.viewModel.fill(), disabled: vm => vm.isLoading}, label),
+            t.if(vm => vm.error, t => t.strong(vm => vm.error))
+        ]);
+    }
+}