[OpenLayers-Users] Missing tiles in OSM map

[Alessandro Candini]

Hi list.
I produce tiles using mapnik (www.mapnik.org) and I use the following 
map definition:

var map = new OpenLayers.Map({
         div: "map",
         allOverlays: true,
         maxExtent: bounds,
         projection: fromProj,
         displayProjection: toProj,
         allowSelection: true,
         controls: [new OpenLayers.Control.PanZoomBar(), new 
OpenLayers.Control.Navigation()],
         });

var layer = new OpenLayers.Layer.OSM(
             layer_dir,
             "tiles/${z}/${x}/${y}.png",
             {zoomLevels: maxZoom, zoomOffset: minZoom, resolutions: res}
         );

map.addLayer(layer);

The problem is that I have a visualization issue in IE and Chrome: the 
missing tiles are represented as pink squares.
Instead in Firefox the visualization is perfect  because it simply uses 
a white background when the tile is missing.

Is there a map or layer parameter to visualize as white the missing tiles?

Thanks in advance,

Alessandro