Index: src/org/openstreetmap/josm/gui/layer/OsmDataLayer.java
===================================================================
--- src/org/openstreetmap/josm/gui/layer/OsmDataLayer.java	(revision 1081)
+++ src/org/openstreetmap/josm/gui/layer/OsmDataLayer.java	(working copy)
@@ -6,8 +6,10 @@
 import static org.openstreetmap.josm.tools.I18n.tr;
 import static org.openstreetmap.josm.tools.I18n.trn;
 
+import java.awt.AlphaComposite;
 import java.awt.Color;
 import java.awt.Component;
+import java.awt.Composite;
 import java.awt.Graphics;
 import java.awt.Graphics2D;
 import java.awt.GridBagLayout;
@@ -137,9 +139,11 @@
         this.data = data;
         this.associatedFile = associatedFile;
         
-        BufferedImage bi = new BufferedImage(15, 15, BufferedImage.TYPE_INT_RGB);
+        BufferedImage bi = new BufferedImage(15, 15, BufferedImage.TYPE_INT_ARGB);
         Graphics2D big = bi.createGraphics();
         big.setColor(Main.pref.getColor(marktr("background"), Color.BLACK));
+        Composite comp = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, .2f);
+        big.setComposite(comp);
         big.fillRect(0,0,15,15);
         big.setColor(Main.pref.getColor(marktr("downloaded Area"), Color.YELLOW));
         big.drawLine(0,15,15,0);