Index: src/org/openstreetmap/josm/gui/layer/OsmDataLayer.java
===================================================================
--- src/org/openstreetmap/josm/gui/layer/OsmDataLayer.java	(revision 11632)
+++ src/org/openstreetmap/josm/gui/layer/OsmDataLayer.java	(working copy)
@@ -413,13 +413,8 @@
             b.grow(100, 100);
             Area a = new Area(b);
 
-            // now successively subtract downloaded areas
-            for (Bounds bounds : data.getDataSourceBounds()) {
-                if (bounds.isCollapsed()) {
-                    continue;
-                }
-                a.subtract(mv.getState().getArea(bounds));
-            }
+            // now subtract downloaded areas
+            a.subtract(data.getDataSourceArea());
 
             // paint remainder
             MapViewPoint anchor = mv.getState().getPointFor(new EastNorth(0, 0));