Index: trunk/src/org/openstreetmap/josm/gui/mappaint/LineElemStyle.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/mappaint/LineElemStyle.java	(revision 5701)
+++ trunk/src/org/openstreetmap/josm/gui/mappaint/LineElemStyle.java	(revision 5702)
@@ -184,5 +184,5 @@
 
         int alpha = 255;
-        Integer pAlpha = Utils.color_float2int(c.get(OPACITY, null, Float.class));
+        Integer pAlpha = Utils.color_float2int(c.get(type.prefix + OPACITY, null, Float.class));
         if (pAlpha != null) {
             alpha = pAlpha;