Don't call tree_view_select on first button click event, it's already done by the tree widget.

=== modified file 'gtk/menu.c'
--- gtk/menu.c	2007-09-15 13:18:50 +0000
+++ gtk/menu.c	2007-10-06 17:58:31 +0000
@@ -2123,7 +2123,7 @@
     }
 
     /* Check if we are on tree_view object */
-    if (widget == tree_view) {
+    if (widget == tree_view && ((GdkEventButton *)event)->button != 1) {
         tree_view_select(widget, (GdkEventButton *) event);
     }