The way I have seen it done (many years ago), is with multiple displays on the screen, one being set up with its position at the bottom serving as a navigation pane and the main part of the screen being set up with the required bottom number of pixels chopped off.
The only advantage being that you did not have to paste a global object on every page.
IIRC, it was necessary to ensure that the menu was set up as the Startup Display and there could be issues if you didn't get the positioning right or if you needed to have certain buttons hidden at certain times, so for those reasons I think I would like Geoff's suggestion a little bit better.