Fixed in 12.0.2:
[ul][li]If the viewer toolbar is turned off it will now be automatically turned back on if the user selects a new toolbar in Preferences. Also the window menu of the viewer now has a command in it to toggle the menu bar on and off.[/li][/ul]
@tbone: If you still get those graphical problems with the toolbar, please let us know, and any hints for how to trigger them.