Fix for being able to select a feature from an invisible layer that uses the Canvas renderer

lib/OpenLayers/Renderer/Canvas.js

@@ -787,6 +787,10 @@ OpenLayers.Renderer.Canvas = OpenLayers.Class(OpenLayers.Renderer, {
      */
     getFeatureIdFromEvent: function(evt) {
         var featureId, feature;
+        
+        // if the drawing canvas isn't visible, return undefined.
+        if (this.root.style.display === "none") return feature;
+        
         if (this.hitDetection) {
             // this dragging check should go in the feature handler
             if (!this.map.dragging) {