Don't re-sort the room list if the user is hovering over it

Fixes vector-im/riot-web#5624

src/components/views/rooms/RoomList.js

@@ -86,6 +86,7 @@ module.exports = React.createClass({
             incomingCallTag: null,
             incomingCall: null,
             selectedTags: [],
+            hover: false,
         };
     },
 
@@ -294,6 +295,17 @@ module.exports = React.createClass({
         this.forceUpdate();
     },
 
+    onMouseEnter: function(ev) {
+        this.setState({hover: true});
+    },
+
+    onMouseLeave: function(ev) {
+        this.setState({hover: false});
+
+        // Refresh the room list just in case the user missed something.
+        this._delayedRefreshRoomList();
+    },
+
     _delayedRefreshRoomList: new rate_limited_func(function() {
         this.refreshRoomList();
     }, 500),
@@ -346,6 +358,11 @@ module.exports = React.createClass({
     },
 
     refreshRoomList: function() {
+        if (this.state.hover) {
+            // Don't re-sort the list if we're hovering over the list
+            return;
+        }
+
         // TODO: ideally we'd calculate this once at start, and then maintain
         // any changes to it incrementally, updating the appropriate sublists
         // as needed.
@@ -693,7 +710,8 @@ module.exports = React.createClass({
         const subListComponents = this._mapSubListProps(subLists);
 
         return (
-            <div ref={this._collectResizeContainer} className="mx_RoomList">
+            <div ref={this._collectResizeContainer} className="mx_RoomList"
+                 onMouseEnter={this.onMouseEnter} onMouseLeave={this.onMouseLeave}>
                 { subListComponents }
             </div>
         );