give the ve layer smooth (but safe) dragging. just like google layer. (Closes #1161) (See #1053)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@5227 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/VirtualEarth.js

@@ -103,10 +103,28 @@ OpenLayers.Layer.VirtualEarth = OpenLayers.Class(
 
         if (this.mapObject != null) {
             try { // this is to catch a Mozilla bug without falling apart
-                this.mapObject.LoadMap(null, null, this.type);
+
+                // The fourth argument is whether the map is 'fixed' -- not 
+                // draggable. See: 
+                // http://blogs.msdn.com/virtualearth/archive/2007/09/28/locking-a-virtual-earth-map.aspx
+                //
+                this.mapObject.LoadMap(null, null, this.type, true);
+                this.mapObject.AttachEvent("onmousedown", function() {return true; });
+
             } catch (e) { }
             this.mapObject.HideDashboard();
         }
+
+        //can we do smooth panning? this is an unpublished method, so we need 
+        // to be careful
+        if ( !this.mapObject ||
+             !this.mapObject.vemapcontrol ||
+             !this.mapObject.vemapcontrol.PanMap ||
+             (typeof this.mapObject.vemapcontrol.PanMap != "function")) {
+
+            this.dragPanMapObject = null;
+        }
+
     },
 
     /** 
@@ -169,6 +187,17 @@ OpenLayers.Layer.VirtualEarth = OpenLayers.Class(
         return this.mapObject.GetCenter();
     },
 
+    /**
+     * APIMethod: dragPanMapObject
+     * 
+     * Parameters:
+     * dX - {Integer}
+     * dY - {Integer}
+     */
+    dragPanMapObject: function(dX, dY) {
+        this.mapObject.vemapcontrol.PanMap(dX, -dY);
+    },
+
     /** 
      * APIMethod: getMapObjectZoom
      *