Index: /trunk/src/org/openstreetmap/josm/io/remotecontrol/AddTagsDialog.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/io/remotecontrol/AddTagsDialog.java	(revision 11183)
+++ /trunk/src/org/openstreetmap/josm/io/remotecontrol/AddTagsDialog.java	(revision 11184)
@@ -192,4 +192,7 @@
                 int r = rowAtPoint(event.getPoint());
                 int c = columnAtPoint(event.getPoint());
+                if (r < 0 || c < 0) {
+                    return getToolTipText();
+                }
                 Object o = getValueAt(r, c);
                 if (c == 1 || c == 2) return o.toString();