SelectFeature control can now select across multiple vector

layers when passed an array of layers instead of a single layer with 
the constructor. This changeset also introduces a new layer type, 
Layer.Vector.RootContainer, which will be set as the topmost layer by 
the SelectFeature control and collect the svg/vml/canvas roots of 
multiple vector layers. r=crschmidt (closes #1666)


git-svn-id: http://svn.openlayers.org/trunk/openlayers@9116 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Renderer/Canvas.js

@@ -15,12 +15,6 @@
  */
 OpenLayers.Renderer.Canvas = OpenLayers.Class(OpenLayers.Renderer, {
 
-    /**
-     * Property: root
-     * {DOMElement} root element of canvas.
-     */
-    root: null,
-
     /**
      * Property: canvas
      * {Canvas} The canvas context object.