Hi Kevin, The Chimera Aqua version has a menu bar at the top of the screen as normal Mac applications do and also at the top of the graphics window. I agree there should be a preference setting to eliminate the in-window menu bar. Here's the reason for this weirdness. There are 13 Chimera dialogs that have their own menu bars and menus. Use of these involves switching between actions in the main window and the dialog repeatedly. With menus for the active window only shown at the top of the screen this interaction becomes very tedious. For this reason I added menu bars within each Chimera window that has its own set of menus. Those in-window menus don't work very well. If you post one menu then put the pointer over an adjacent menu it will not pop up. An even worse atrocity in Aqua Chimera is that it implements "focus follows mouse". As the pointer is moved over the various Chimera windows the one underneath becomes active. This again was added because common Chimera usage involves switching frequently between windows and the normal Mac "click to focus" behavior is inconvenient for this. We would like instead to use "click through" where the first mouse click on a window both activates that window and presses the button or activates the entry field that was clicked on. I have not been able to do this in Aqua Tk, the windowing toolkit we use. The problem we're facing is that the Chimera user interface with its many windows and frequent switching between windows is poorly suited to the Mac GUI conventions. The in-window menus and focus-follows-mouse mode are a first stab at a compromise solution -- still much to be desired. Tom Kevin Walzer wrote: The latest build of Chimera from 7/3/08 on OS X/Aqua (10.5.4) includes menubars at the top of the screen (the standard OS X behavior) *and* on the main toplevel window itself, as on Windows and X11. This behavior is simply weird--two menus? It can only b e regarded as a bug, not a feature. What purpose does it serve? The correct Mac behavior can be restored by commenting out lines 1470-1476 of tkgui.py. If some of your Mac users are requesting this kind of behavior in menubars, at the very least the non- standard window-based menubar should be a preferences item that can be toggled off.