Although user can get menu bar visible by pressing right mouse button down at any place it doesnt work in every application. Some programs bring context menus, some other zips window, some other does nothing -- it isnt systematic.
It is supposed to be though. Commodore did put out a style guide, that most serious apps do follow. But yeah, there will always be those apps that stray from the standard. A great example was DeluxePaint, which used the right mouse button to good use.
However, despite all it's peculiarities, it was still an easy system to use. In a weird way, it just made sense. Perhaps that's only because it was my first computer, or that back then there was no universal standards for UI design. In hind sight, the Amiga needed a three button mouse (with a scroll wheel preferably ;-) ).
- Mike
