fix(message-list-toolbar): Fix observable for selection & focused thread

internal_packages/thread-list/lib/message-list-toolbar.jsx

@@ -8,23 +8,16 @@ import InjectsToolbarButtons, {ToolbarRole} from './injects-toolbar-buttons'
 
 function getObservable() {
   return (
-    Rx.Observable.merge(
+    Rx.Observable.combineLatest(
       Rx.Observable.fromStore(FocusedContentStore),
       ThreadListStore.selectionObservable(),
+      (store, items) => ({focusedThread: store.focused('thread'), items})
     )
-    .map((data) => {
-      const storeChanged = data === FocusedContentStore
-      const selectionChanged = data instanceof Array
-
-      if (storeChanged) {
-        const focusedThread = FocusedContentStore.focused('thread')
-        if (focusedThread) {
-          return [focusedThread]
-        }
-      } else if (selectionChanged) {
-        return data
+    .map(({focusedThread, items}) => {
+      if (focusedThread) {
+        return [focusedThread]
       }
-      return []
+      return items
     })
   )
 }

src/global/nylas-observables.coffee

@@ -86,12 +86,11 @@ Rx.Observable.fromListSelection = (originStore) =>
       )
       return
     )
-    return {
-      dispose: =>
-        if dataSourceDisposable
-          dataSourceDisposable.dispose()
-        disposable.dispose()
-    }
+    dispose = =>
+      if dataSourceDisposable
+        dataSourceDisposable.dispose()
+      disposable.dispose()
+    return Rx.Disposable.create(dispose)
   )
 
 Rx.Observable.fromConfig = (configKey) =>