Never allow PaneContainer::root to be null

src/pane-axis-view.coffee

@@ -8,6 +8,9 @@ class PaneAxisView extends View
     @onChildAdded(child) for child in @model.children
     @subscribe @model.children, 'changed', @onChildrenChanged
 
+  afterAttach: ->
+    @container = @closest('.panes').view()
+
   viewForModel: (model) ->
     viewClass = model.getViewClass()
     model._view ?= new viewClass(model)
@@ -26,9 +29,5 @@ class PaneAxisView extends View
     view = @viewForModel(child)
     view.detach()
     PaneView ?= require './pane-view'
-
     if view instanceof PaneView and view.model.isDestroyed()
-      @getContainer()?.trigger 'pane:removed', [view]
-
-  getContainer: ->
-    @closest('.panes').view()
+      @container?.trigger 'pane:removed', [view]

src/pane-container-view.coffee

@@ -32,9 +32,6 @@ class PaneContainerView extends View
   getRoot: ->
     @children().first().view()
 
-  setRoot: (root) ->
-    @model.root = root?.model
-
   onRootChanged: (root) =>
     focusedElement = document.activeElement if @hasFocus()
 

src/pane-container.coffee

@@ -9,7 +9,7 @@ class PaneContainer extends Model
   Serializable.includeInto(this)
 
   @properties
-    root: null
+    root: -> new Pane
     activePane: null
 
   previousRoot: null
@@ -75,11 +75,8 @@ class PaneContainer extends Model
     root.parent = this
     root.container = this
 
-    if root instanceof Pane
-      @activePane ?= root
-      @subscribe root, 'destroyed', =>
-        @activePane = null
-        @root = null
+
+    @activePane ?= root if root instanceof Pane
 
   destroyEmptyPanes: ->
     pane.destroy() for pane in @getPanes() when pane.items.length is 0

src/pane-view.coffee

@@ -102,6 +102,7 @@ class PaneView extends View
     @focus() if @model.focused and onDom
 
     return if @attached
+    @container = @closest('.panes').view()
     @attached = true
     @trigger 'pane:attached', [this]
 
@@ -118,7 +119,7 @@ class PaneView extends View
 
   # Public: Returns the next pane, ordered by creation.
   getNextPane: ->
-    panes = @getContainer()?.getPanes()
+    panes = @container?.getPanes()
     return unless panes.length > 1
     nextIndex = (panes.indexOf(this) + 1) % panes.length
     panes[nextIndex]
@@ -194,10 +195,6 @@ class PaneView extends View
 
   splitDown: (items...) -> @model.splitDown({items})._view
 
-  # Private:
-  getContainer: ->
-    @closest('.panes').view()
-
   beforeRemove: ->
     @model.destroy() unless @model.isDestroyed()
 

src/pane.coffee

@@ -125,7 +125,7 @@ class Pane extends Model
   #     The item to add. It can be a model with an associated view or a view.
   # * index:
   #     An optional index at which to add the item. If omitted, the item is
-  #     added to the end.
+  #     added after the current active item.
   #
   # Returns the added item
   addItem: (item, index=@getActiveItemIndex() + 1) ->
@@ -136,6 +136,21 @@ class Pane extends Model
     @emit 'item-added', item, index
     item
 
+  # Public: Adds the given items to the pane.
+  #
+  # * items:
+  #     An {Array} of items to add. Items can be models with associated views
+  #     or views. Any items that are already present in items will not be added.
+  # * index:
+  #     An optional index at which to add the item. If omitted, the item is
+  #     added after the current active item.
+  #
+  # Returns an {Array} of the added items
+  addItems: (items, index=@getActiveItemIndex() + 1) ->
+    items = items.filter (item) => not (item in @items)
+    @addItem(item, index + i) for item, i in items
+    items
+
   # Private:
   removeItem: (item, destroying) ->
     index = @items.indexOf(item)
@@ -187,6 +202,9 @@ class Pane extends Model
   destroyInactiveItems: ->
     @destroyItem(item) for item in @getItems() when item isnt @activeItem
 
+  destroy: ->
+    super unless @container?.getPanes().length is 1
+
   # Private: Called by model superclass.
   destroyed: ->
     @container.activateNextPane() if @isActive()