put zoombar slider at the correct zoom level on first draw (not just always at the end)

git-svn-id: http://svn.openlayers.org/branches/openlayers/2.0@1306 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Control/PanZoomBar.js

@@ -77,9 +77,9 @@ OpenLayers.Control.PanZoomBar.prototype =
         var imgLocation = OpenLayers.Util.getImagesLocation();
         
         var id = "OpenLayers_Control_PanZoomBar_Slider" + this.map.id;
+        var zoomsToEnd = this.map.getNumZoomLevels() - 1 - this.map.getZoom();
         var slider = OpenLayers.Util.createAlphaImageDiv(id,
-                       centered.add(-1, 
-                        (this.map.getNumZoomLevels()-1) * this.zoomStopHeight), 
+                       centered.add(-1, zoomsToEnd * this.zoomStopHeight), 
                        new OpenLayers.Size(20,9), 
                        imgLocation+"slider.png",
                        "absolute");