diff --git a/src/components/structures/LoggedInView.js b/src/components/structures/LoggedInView.js
index d6b374aac8..11acb942b6 100644
--- a/src/components/structures/LoggedInView.js
+++ b/src/components/structures/LoggedInView.js
@@ -35,7 +35,7 @@ import RoomListStore from "../../stores/RoomListStore";
 import TagOrderActions from '../../actions/TagOrderActions';
 import RoomListActions from '../../actions/RoomListActions';
 import ResizeHandle from '../views/elements/ResizeHandle';
-import {makeResizeable, CollapseDistributor} from '../../resizer'
+import {Resizer, CollapseDistributor} from '../../resizer'
 // We need to fetch each pinned message individually (if we don't already have it)
 // so each pinned message may trigger a request. Limit the number per room for sanity.
 // NB. this is just for server notices rather than pinned messages in general.
@@ -98,17 +98,18 @@ const LoggedInView = React.createClass({
             vertical: "mx_ResizeHandle_vertical",
             reverse: "mx_ResizeHandle_reverse"
         };
-        const config = {
+        const collapseConfig = {
             toggleSize: 260 - 50,
             onCollapsed: (collapsed) => {
                 this.setState({collapseLhs: collapsed});
             }
         };
-        makeResizeable(
+        const resizer = new Resizer(
             this.resizeContainer,
-            classNames,
             CollapseDistributor,
-            config);
+            collapseConfig);
+        resizer.setClassNames(classNames);
+        resizer.attach();
     },
 
     componentWillMount: function() {
diff --git a/src/resizer/event.js b/src/resizer/event.js
deleted file mode 100644
index 7619a3e91d..0000000000
--- a/src/resizer/event.js
+++ /dev/null
@@ -1,72 +0,0 @@
-import {Sizer} from "./sizer";
-
-/*
-classNames:
-    // class on resize-handle
-    handle: string
-    // class on resize-handle
-    reverse: string
-    // class on resize-handle
-    vertical: string
-    // class on container
-    resizing: string
-*/
-
-function makeResizeable(container, classNames, distributorCtor, distributorCfg = undefined, sizerCtor = Sizer) {
-
-    function isResizeHandle(el) {
-        return el && el.classList.contains(classNames.handle);
-    }
-
-    function handleMouseDown(event) {
-        const target = event.target;
-        if (!isResizeHandle(target) || target.parentElement !== container) {
-            return;
-        }
-        // prevent starting a drag operation
-        event.preventDefault();
-        // mark as currently resizing
-        if (classNames.resizing) {
-            container.classList.add(classNames.resizing);
-        }
-
-        const resizeHandle = event.target;
-        const vertical = resizeHandle.classList.contains(classNames.vertical);
-        const reverse = resizeHandle.classList.contains(classNames.reverse);
-        const direction = reverse ? 0 : -1;
-
-        const sizer = new sizerCtor(container, vertical, reverse);
-
-        const items = Array.from(container.children).filter(el => {
-            return !isResizeHandle(el) && (
-                isResizeHandle(el.previousElementSibling) ||
-                isResizeHandle(el.nextElementSibling));
-        });
-        const prevItem = resizeHandle.previousElementSibling;
-        const handleIndex = items.indexOf(prevItem) + 1;
-        const distributor = new distributorCtor(
-            container, items, handleIndex,
-            direction, sizer, distributorCfg);
-
-        const onMouseMove = (event) => {
-            const offset = sizer.offsetFromEvent(event);
-            distributor.resize(offset);
-        };
-
-        const body = document.body;
-        const onMouseUp = (event) => {
-            if (classNames.resizing) {
-                container.classList.remove(classNames.resizing);
-            }
-            const offset = sizer.offsetFromEvent(event);
-            distributor.finish(offset);
-            body.removeEventListener("mouseup", onMouseUp, false);
-            body.removeEventListener("mousemove", onMouseMove, false);
-        };
-        body.addEventListener("mouseup", onMouseUp, false);
-        body.addEventListener("mousemove", onMouseMove, false);
-    }
-    container.addEventListener("mousedown", handleMouseDown, false);
-}
-
-module.exports = {makeResizeable};
diff --git a/src/resizer/index.js b/src/resizer/index.js
index fba384ebb9..4b335ce4a4 100644
--- a/src/resizer/index.js
+++ b/src/resizer/index.js
@@ -1,9 +1,9 @@
 import {Sizer} from "./sizer";
 import {FixedDistributor, CollapseDistributor, PercentageDistributor} from "./distributors";
-import {makeResizeable} from "./event";
+import {Resizer} from "./resizer";
 
 module.exports = {
-    makeResizeable,
+    Resizer,
     Sizer,
     FixedDistributor,
     CollapseDistributor,
diff --git a/src/resizer/resizer.js b/src/resizer/resizer.js
new file mode 100644
index 0000000000..a2affa53ac
--- /dev/null
+++ b/src/resizer/resizer.js
@@ -0,0 +1,94 @@
+import {Sizer} from "./sizer";
+
+/*
+classNames:
+    // class on resize-handle
+    handle: string
+    // class on resize-handle
+    reverse: string
+    // class on resize-handle
+    vertical: string
+    // class on container
+    resizing: string
+*/
+
+export class Resizer {
+    constructor(container, distributorCtor, distributorCfg, sizerCtor = Sizer) {
+        this.container = container;
+        this.distributorCtor = distributorCtor;
+        this.distributorCfg = distributorCfg;
+        this.sizerCtor = sizerCtor;
+        this.classNames = {
+            handle: "resizer-handle",
+            reverse: "resizer-reverse",
+            vertical: "resizer-vertical",
+            resizing: "resizer-resizing",
+        };
+        this.mouseDownHandler = (event) => this._onMouseDown(event);
+    }
+
+    setClassNames(classNames) {
+        this.classNames = classNames;
+    }
+
+    attach() {
+        this.container.addEventListener("mousedown", this.mouseDownHandler, false);
+    }
+
+    detach() {
+        this.container.removeEventListener("mousedown", this.mouseDownHandler, false);
+    }
+
+    _isResizeHandle(el) {
+        return el && el.classList.contains(this.classNames.handle);
+    }
+
+    _onMouseDown(event) {
+        const target = event.target;
+        if (!this._isResizeHandle(target) || target.parentElement !== this.container) {
+            return;
+        }
+        // prevent starting a drag operation
+        event.preventDefault();
+        // mark as currently resizing
+        if (this.classNames.resizing) {
+            this.container.classList.add(this.classNames.resizing);
+        }
+
+        const resizeHandle = event.target;
+        const vertical = resizeHandle.classList.contains(this.classNames.vertical);
+        const reverse = resizeHandle.classList.contains(this.classNames.reverse);
+        const direction = reverse ? 0 : -1;
+
+        const sizer = new this.sizerCtor(this.container, vertical, reverse);
+
+        const items = Array.from(this.container.children).filter(el => {
+            return !this._isResizeHandle(el) && (
+                this._isResizeHandle(el.previousElementSibling) ||
+                this._isResizeHandle(el.nextElementSibling));
+        });
+        const prevItem = resizeHandle.previousElementSibling;
+        const handleIndex = items.indexOf(prevItem) + 1;
+        const distributor = new this.distributorCtor(
+            this.container, items, handleIndex,
+            direction, sizer, this.distributorCfg);
+
+        const onMouseMove = (event) => {
+            const offset = sizer.offsetFromEvent(event);
+            distributor.resize(offset);
+        };
+
+        const body = document.body;
+        const onMouseUp = (event) => {
+            if (this.classNames.resizing) {
+                this.container.classList.remove(this.classNames.resizing);
+            }
+            const offset = sizer.offsetFromEvent(event);
+            distributor.finish(offset);
+            body.removeEventListener("mouseup", onMouseUp, false);
+            body.removeEventListener("mousemove", onMouseMove, false);
+        };
+        body.addEventListener("mouseup", onMouseUp, false);
+        body.addEventListener("mousemove", onMouseMove, false);
+    }
+}