     @prefixedClasses.add PANE_CLS
     @syncProperty @context, 'transition start end width height'
 
+    # Set of pane transitions.
+    @_transitions = transitions
+
     @on 'transition:in', ->
-      transitions[@transition].in?.call @
+      @_transitions[@transition].in?.call @
       #@setDisplaySize()
 
     @on 'transition:out', ->
-      transitions[@transition].out?.call @
+      @_transitions[@transition].out?.call @
 
   # Clone shared view-model properties.
   @cloneProperty Pane, 'transition start end width height center'
+
+
+  ###*
+  # Set of transition utilities for positioning and sizing the pane.
+  #
+  # @member _transitions
+  # @memberof stout-ui/pane/PaneView#
+  # @protected
+  ###
 
 
   ###*

      @setPaneTransitionClasses()
      @resetSizeAndPosition()
      @setDisplaySize()
      transitions[@transition].setupIn.call(@).then =>
        super(time).then =>
          @root.style.transform = ''
          window.addEventListener 'resize', @_resizeHandler

      because the pane is already hidden."
    else
      @setPaneTransitionClasses()
      @_transitions[@transition].setupOut.call(@).then =>
        super(time).then =>
          window.removeEventListener 'resize', @_resizeHandler

