Patch from Tim Schaub to Box.js to make display better in IE.

git-svn-id: http://svn.openlayers.org/trunk/openlayers@1523 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Marker/Box.js

@@ -24,6 +24,7 @@ OpenLayers.Marker.Box.prototype = Object.extend( new OpenLayers.Marker(), {
         if (arguments.length > 0) {
             this.bounds = bounds;
             this.div    = OpenLayers.Util.createDiv();
+            this.div.style.overflow = 'hidden';
             this.events = new OpenLayers.Events(this, this.div, null);
             this.setBorder(borderColor, borderWidth);
         }