Index: applications/editors/josm/plugins/mappaint/src/mappaint/MapPaintVisitor.java
===================================================================
--- applications/editors/josm/plugins/mappaint/src/mappaint/MapPaintVisitor.java	(revision 5022)
+++ applications/editors/josm/plugins/mappaint/src/mappaint/MapPaintVisitor.java	(revision 5024)
@@ -31,4 +31,5 @@
     protected boolean zoomLevelDisplay;
     protected boolean fillAreas;
+    protected int fillAlpha;
     protected Color untaggedColor;
     protected Color textColor;
@@ -168,4 +169,7 @@
 		Polygon polygon = new Polygon();
 		Point p;
+		// set the opacity (alpha) level of the filled polygon
+		Color coloura = new Color( colour.getRed(), colour.getGreen(), colour.getBlue(), fillAlpha);
+		
 		for (Node n : w.nodes)
 		{
@@ -175,5 +179,5 @@
 
 		g.setColor( w.selected ?
-						selectedColor : colour);
+						selectedColor : coloura);
 
 		g.fillPolygon(polygon);
@@ -306,4 +310,17 @@
 		fillAreas = Main.pref.getBoolean("mappaint.fillareas", true);
 		
+		/* XXX - there must be a better way to get a bounded Integer pref! */
+		try {
+			fillAlpha = Integer.valueOf(Main.pref.get("mappaint.fillalpha", "50"));
+			if(fillAlpha < 0) {
+				fillAlpha = 0;
+			}
+			if(fillAlpha > 255) {
+				fillAlpha = 255;
+			}
+		} catch (NumberFormatException nfe) {
+			fillAlpha = 50;
+		}
+		
 		Collection<Way> noAreaWays = new LinkedList<Way>();