Preserve tree view focus state on refresh

spec/extensions/tree-view-spec.coffee

@@ -60,6 +60,19 @@ describe "TreeView", ->
       expect(newTreeView.selectedEntry()).toMatchSelector(".file:contains(sample.js)")
       expect(newTreeView.find(".directory:contains(zed)")).toHaveClass("expanded")
 
+    it "restores the focus state of the tree view", ->
+      treeView.attachToDom()
+      treeView.focus()
+      expect(treeView).toMatchSelector ':focus'
+
+      newRootView = RootView.deserialize(rootView.serialize())
+      rootView.remove()
+      newRootView.attachToDom()
+      newRootView.activateExtension(TreeView)
+
+      newTreeView = newRootView.find(".tree-view").view()
+      expect(newTreeView).toMatchSelector ':focus'
+
   describe "when a directory's disclosure arrow is clicked", ->
     it "expands / collapses the associated directory", ->
       subdir = treeView.root.find('.entries > li:contains(dir/)').view()

src/extensions/tree-view/tree-view.coffee

@@ -30,9 +30,11 @@ class TreeView extends View
     treeView = new TreeView(rootView)
     treeView.root.deserializeEntryExpansionStates(state.directoryExpansionStates)
     treeView.selectEntryForPath(state.selectedPath)
+    treeView.focusAfterAttach = state.hasFocus
     treeView
 
   root: null
+  focusAfterAttach: false
 
   initialize: (@rootView) ->
     @on 'click', '.entry', (e) =>
@@ -54,9 +56,13 @@ class TreeView extends View
     @on 'tree-view:unfocus', => @rootView.activeEditor()?.focus()
     @rootView.on 'tree-view:focus', => this.focus()
 
+  afterAttach: (onDom) ->
+    @focus() if @focusAfterAttach
+
   serialize: ->
     directoryExpansionStates: @root.serializeEntryExpansionStates()
     selectedPath: @selectedEntry()?.getPath()
+    hasFocus: @is(':focus')
 
   deactivate: ->
     @root.unwatchEntries()