don't re-append the geometry node to root if it is already there to keep it in place and to prevent z-index to change, r=elemoine (closes #1066)

Thanks Eric for giving me the opportunity to have my first commit in OpenLayers trunk

git-svn-id: http://svn.openlayers.org/trunk/openlayers@5772 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Renderer/Elements.js

@@ -134,7 +134,11 @@ OpenLayers.Renderer.Elements = OpenLayers.Class(OpenLayers.Renderer, {
             
             //now actually draw the node, and style it
             node = this.drawGeometryNode(node, geometry);
-            this.root.appendChild(node);
+            
+            // append the node to root (but only if it's new)
+	        if (node.parentNode != this.root) { 
+	            this.root.appendChild(node); 
+	        }
             this.postDraw(node);
         } else {
             node = OpenLayers.Util.getElement(geometry.id);