Index: trunk/src/org/openstreetmap/josm/gui/MenuScroller.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/MenuScroller.java	(revision 14172)
+++ trunk/src/org/openstreetmap/josm/gui/MenuScroller.java	(revision 14173)
@@ -316,5 +316,5 @@
 
             if (mustSCroll) {
-                firstIndex = Math.max(topFixedCount, firstIndex);
+                firstIndex = Math.min(menuItems.length-1, Math.max(topFixedCount, firstIndex));
                 int scrollCount = computeScrollCount(firstIndex);
                 firstIndex = Math.min(menuItems.length - scrollCount, firstIndex);