Index: /trunk/src/org/openstreetmap/josm/gui/layer/markerlayer/ButtonMarker.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/layer/markerlayer/ButtonMarker.java	(revision 4283)
+++ /trunk/src/org/openstreetmap/josm/gui/layer/markerlayer/ButtonMarker.java	(revision 4284)
@@ -27,5 +27,5 @@
 
     public ButtonMarker(LatLon ll, String buttonImage, MarkerLayer parentLayer, double time, double offset) {
-        super(ll, null, buttonImage, parentLayer, time, offset);
+        super(ll, "", buttonImage, parentLayer, time, offset);
         buttonRectangle = new Rectangle(0, 0, symbol.getIconWidth(), symbol.getIconHeight());
     }
Index: /trunk/src/org/openstreetmap/josm/gui/layer/markerlayer/PlayHeadMarker.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/layer/markerlayer/PlayHeadMarker.java	(revision 4283)
+++ /trunk/src/org/openstreetmap/josm/gui/layer/markerlayer/PlayHeadMarker.java	(revision 4284)
@@ -59,5 +59,5 @@
 
     private PlayHeadMarker() {
-        super(new LatLon(0.0,0.0), null,
+        super(new LatLon(0.0,0.0), "",
                 Main.pref.get("marker.audiotracericon", "audio-tracer"),
                 null, -1.0, 0.0);