fix focus() being called too often

routes/_components/status/Notification.html

@@ -42,7 +42,8 @@
   export default {
     oncreate() {
       let focusSelector = this.get('focusSelector')
-      if (this.refs.node && focusSelector) {
+      if (this.refs.node && focusSelector &&
+          this.store.getForCurrentTimeline('shouldRestoreFocus')) {
         restoreFocus(this.refs.node, focusSelector)
       }
     },

routes/_components/status/Status.html

@@ -113,7 +113,8 @@
         registerClickDelegate(delegateKey, (e) => this.onClickOrKeydown(e))
       }
       let focusSelector = this.get('focusSelector')
-      if (this.refs.node && focusSelector) {
+      if (this.refs.node && focusSelector &&
+          this.store.getForCurrentTimeline('shouldRestoreFocus')) {
         restoreFocus(this.refs.node, focusSelector)
       }
     },

routes/_components/timeline/Timeline.html

@@ -177,6 +177,16 @@
       },
       onScrollTopChanged(scrollTop) {
         this.set({scrollTop: scrollTop})
+        if (!this.get('observedOnScrollTopChanged')) {
+          // ignore the first scroll top change, e.g.
+          // because we forced a scroll top change
+          this.set({observedOnScrollTopChanged: true})
+        } else {
+          // after that, don't allow statuses/notifications to call focus()
+          // after we've already started scrolling. that causes scrolling to
+          // jump around
+          this.store.setForCurrentTimeline({shouldRestoreFocus: false})
+        }
       },
       onScrollToBottom() {
         if (!this.store.get('initialized') ||
@@ -233,7 +243,10 @@
       },
       setupFocus() {
         this.onPushState = this.onPushState.bind(this)
-        this.store.setForCurrentTimeline({ignoreBlurEvents: false})
+        this.store.setForCurrentTimeline({
+          ignoreBlurEvents: false,
+          shouldRestoreFocus: true
+        })
         window.addEventListener('pushState', this.onPushState)
       },
       teardownFocus() {

routes/_store/computations/timelineComputations.js

@@ -18,6 +18,7 @@ export function timelineComputations (store) {
   computeForTimeline(store, 'showHeader', false)
   computeForTimeline(store, 'shouldShowHeader', false)
   computeForTimeline(store, 'timelineItemIdsAreStale', false)
+  computeForTimeline(store, 'shouldRestoreFocus', false)
 
   store.compute('firstTimelineItemId', ['timelineItemIds'], (timelineItemIds) => {
     return timelineItemIds && timelineItemIds[0]

routes/_store/mixins/timelineMixins.js

@@ -20,6 +20,12 @@ export function timelineMixins (Store) {
     return root && root[instanceName] && root[instanceName][timelineName]
   }
 
+  Store.prototype.getForCurrentTimeline = function (key) {
+    let instanceName = this.get('currentInstance')
+    let timelineName = this.get('currentTimeline')
+    return this.getForTimeline(instanceName, timelineName, key)
+  }
+
   Store.prototype.getAllTimelineData = function (instanceName, key) {
     let root = this.get(`timelineData_${key}`) || {}
     return root[instanceName] || {}