Give handlers a non-API evt property - this to be used by other controls in the library only. Eventually, we may decide to restructure this. (Closes #902)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@4062 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Handler.js

@@ -72,6 +72,16 @@ OpenLayers.Handler = OpenLayers.Class({
      * {Boolean}
      */
     active: false,
+    
+    /**
+     * Property: evt
+     * {Event} This property references the last event handled by the handler.
+     *     Note that this property is not part of the stable API.  Use of the
+     *     evt property should be restricted to controls in the library
+     *     or other applications that are willing to update with changes to
+     *     the OpenLayers code.
+     */
+    evt: null,
 
     /**
      * Constructor: OpenLayers.Handler
@@ -198,7 +208,8 @@ OpenLayers.Handler = OpenLayers.Class({
     */
     register: function (name, method) {
         // TODO: deal with registerPriority in 3.0
-        this.map.events.registerPriority(name, this, method);   
+        this.map.events.registerPriority(name, this, method);
+        this.map.events.registerPriority(name, this, this.setEvent);
     },
 
     /**
@@ -207,6 +218,29 @@ OpenLayers.Handler = OpenLayers.Class({
     */
     unregister: function (name, method) {
         this.map.events.unregister(name, this, method);   
+        this.map.events.unregister(name, this, this.setEvent);
+    },
+    
+    /**
+     * Method: setEvent
+     * With each registered browser event, the handler sets its own evt
+     *     property.  This property can be accessed by controls if needed
+     *     to get more information about the event that the handler is
+     *     processing.
+     *
+     * This allows modifier keys on the event to be checked (alt, shift,
+     *     and ctrl cannot be checked with the keyboard handler).  For a
+     *     control to determine which modifier keys are associated with the
+     *     event that a handler is currently processing, it should access
+     *     (code)handler.evt.altKey || handler.evt.shiftKey ||
+     *     handler.evt.ctrlKey(end).
+     *
+     * Parameters:
+     * evt - {Event} The browser event.
+     */
+    setEvent: function(evt) {
+        this.evt = evt;
+        return true;
     },
 
     /**