Index: trunk/src/org/openstreetmap/josm/actions/FullscreenToggleAction.java
===================================================================
--- trunk/src/org/openstreetmap/josm/actions/FullscreenToggleAction.java	(revision 19311)
+++ trunk/src/org/openstreetmap/josm/actions/FullscreenToggleAction.java	(revision 19314)
@@ -57,5 +57,5 @@
         Config.getPref().putBoolean("draw.fullscreen", isSelected());
         notifySelectedState();
-        setMode();
+        safeSetMode();
     }
 
@@ -65,5 +65,15 @@
     public void initial() {
         if (isSelected()) {
-            setMode();
+            safeSetMode();
+        }
+    }
+
+    protected void safeSetMode() {
+        try {
+            this.setMode();
+        } catch (Exception exception) {
+            // Something happened. Disable fullscreen.
+            Config.getPref().put("draw.fullscreen", null);
+            throw exception;
         }
     }