Adding a beforefeatureselected event to the vector layer events. If a listener returns false, the feature is not selected. The modify feature control now listens for beforefeatureselected and triggers beforefeaturemodified. If a listener returns false, feature modification never begins. r=elemione,ahocevar (closes #1427)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@7616 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Control/ModifyFeature.js

@@ -201,6 +201,7 @@ OpenLayers.Control.ModifyFeature = OpenLayers.Class(OpenLayers.Control, {
             layer, selectOptions
         );
         this.layer.events.on({
+            "beforefeatureselected": this.beforeSelectFeature,
             "featureselected": this.selectFeature,
             "featureunselected": this.unselectFeature,
             scope: this
@@ -239,6 +240,7 @@ OpenLayers.Control.ModifyFeature = OpenLayers.Class(OpenLayers.Control, {
      */
     destroy: function() {
         this.layer.events.un({
+            "beforefeatureselected": this.beforeSelectFeature,
             "featureselected": this.selectFeature,
             "featureunselected": this.unselectFeature,
             scope: this
@@ -287,6 +289,20 @@ OpenLayers.Control.ModifyFeature = OpenLayers.Class(OpenLayers.Control, {
         }
         return deactivated;
     },
+    
+    /**
+     * Method: beforeSelectFeature
+     * Called before a feature is selected.
+     *
+     * Parameters:
+     * object - {Object} Object with a feature property referencing the
+     *     selected feature.
+     */
+    beforeSelectFeature: function(object) {
+        return this.layer.events.triggerEvent(
+            "beforefeaturemodified", {feature: object.feature}
+        );
+    },
 
     /**
      * Method: selectFeature
@@ -301,8 +317,6 @@ OpenLayers.Control.ModifyFeature = OpenLayers.Class(OpenLayers.Control, {
         this.resetVertices();
         this.dragControl.activate();
         this.onModificationStart(this.feature);
-        this.layer.events.triggerEvent("beforefeaturemodified", 
-                                       {feature: this.feature});
     },
 
     /**