     else
       @container.classList.remove DRAWER_CONTAINER_CLS
       @viewport.classList.remove DRAWER_VIEWPORT_CLS
+
+    return p
 
 
   ###*

    # Set the pane transition type.
    if @behavior is 'push'
      @transition = 'fade'
      @getRenderedDimensions().then (d) =>
        @root.style.left = -d.width + 'px'
    else
      @transition = 'overlay'

  open: =>
    if @canTransitionIn()
      @_setElementClasses 'opening'
      @_setupDrawer().then =>
        @transitionIn().then => @_setElementClasses 'open'
    else
      Promise.rejected()

