tweak

Fltk/FlGui.cpp

@@ -98,7 +98,7 @@ FlGui::FlGui(int argc, char **argv)
 
   // add new box types used in graphic window (dx dy dw dh)
   Fl::set_boxtype(GMSH_SIMPLE_RIGHT_BOX, simple_right_box_draw, 0, 0, 1, 0);
-  Fl::set_boxtype(GMSH_SIMPLE_TOP_BOX, simple_top_box_draw, 0, 1, 0, 0);
+  Fl::set_boxtype(GMSH_SIMPLE_TOP_BOX, simple_top_box_draw, 0, 1, 0, 1);
 
   // add global shortcuts
   Fl::add_handler(globalShortcut);