Only draw transparent images if the tiles are transparent.

git-svn-id: http://svn.openlayers.org/trunk/openlayers@681 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/Grid.js

@@ -146,7 +146,7 @@ OpenLayers.Layer.Grid.prototype = Object.extend( new OpenLayers.Layer(), {
                                         new OpenLayers.Pixel(tileoffsetx - parseInt(this.map.layerContainerDiv.style.left),
                                                              tileoffsety - parseInt(this.map.layerContainerDiv.style.top))
                                                             );
-                tile.draw();
+                tile.draw((this.params.TRANSPARENT == true));
                 row.append(tile);
      
                 tileoffsetlon += tilelon;