implement basic local echo for resetting unread message count when opening a room without a scroll offset. hopefully largely fixes https://github.com/vector-im/vector-web/issues/967

src/components/structures/RoomView.js

@@ -132,8 +132,7 @@ module.exports = React.createClass({
         MatrixClientPeg.get().on("Room.timeline", this.onRoomTimeline);
         MatrixClientPeg.get().on("Room.accountData", this.onRoomAccountData);
         MatrixClientPeg.get().on("RoomState.members", this.onRoomStateMember);
-        // xchat-style tab complete, add a colon if tab
+
-        // completing at the start of the text
         this.tabComplete = new TabComplete({
             allowLooping: false,
             autoEnterTabComplete: true,
@@ -143,7 +142,6 @@ module.exports = React.createClass({
             }
         });
 
-
         // if this is an unknown room then we're in one of three states:
         // - This is a room we can peek into (search engine) (we can /peek)
         // - This is a room we can publicly join or were invited to. (we can /join)

src/components/structures/ScrollPanel.js

@@ -56,7 +56,7 @@ if (DEBUG_SCROLL) {
  *     offset.  We don't save the absolute scroll offset, because that would be
  *     affected by window width, zoom level, amount of scrollback, etc. Instead
  *     we save an identifier for the last fully-visible message, and the number
- *     of pixels the window was scrolled below it - which is hopefully be near
+ *     of pixels the window was scrolled below it - which is hopefully near
  *     enough.
  *
  * The 'stickyBottom' property controls the behaviour when we reach the bottom

src/components/structures/TimelinePanel.js

@@ -399,6 +399,14 @@ var TimelinePanel = React.createClass({
     sendReadReceipt: function() {
         if (!this.refs.messagePanel) return;
 
+        // if we are scrolled to the bottom, do a quick-reset of our unreadNotificationCount
+        // to avoid having to wait from the remote echo from the homeserver.
+        if (this.getScrollState().stuckAtBottom) {
+            this.props.room.setUnreadNotificationCount('total', 0);
+            this.props.room.setUnreadNotificationCount('highlight', 0);
+            // XXX: i'm a bit surprised we don't have to emit an event or dispatch to make the echo picked up
+        }
+
         var currentReadUpToEventId = this._getCurrentReadReceipt(true);
         var currentReadUpToEventIndex = this._indexForEventId(currentReadUpToEventId);