give Control classes same setMap() functionality as Layer

git-svn-id: http://svn.openlayers.org/trunk/openlayers@936 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Control.js

@@ -24,6 +24,16 @@ OpenLayers.Control.prototype = {
         Object.extend(this, options);
     },
 
+    /** Set the map property for the control. This is done through an accessor
+     *   so that subclasses can override this and take special action once 
+     *   they have their map variable set. 
+     * 
+     * @param {OpenLayers.Map} map
+     */
+    setMap: function(map) {
+        this.map = map;
+    },
+  
     /**
     * @param {OpenLayers.Pixel} px
     *

lib/OpenLayers/Map.js

@@ -318,7 +318,7 @@ OpenLayers.Map.prototype = {
     * @param {OpenLayers.Pixel} px
     */    
     addControl: function (control, px) {
-        control.map = this;
+        control.setMap(this);
         this.controls.push(control);
         var div = control.draw(px);
         if (div) {