Innovation in a GUI needs to be done by slow and careful incremental improvement. New features should be inserted somewhere that they won't cause a user any difficulty until he is ready to try them out. Menus (be they start, right-click, or hover) are a good way to accomplish this. Magic pixels that dump you into something you've never seen before when you get your mouse near to them, are a very bad way.
If the GUI won't work on some other class of device, you need a new GUI for that class of device. Or you can implement a mode-switcher, provided it's hard to get into if you don't know what you are doing, and easy to escape from if you blunder in to its first stage without knowing what it is.
An example that's only tangentially Microsoft. I was recently called in to look at two "broken" laptops where the mouse-pad had stopped working. It took a while to discover that Alt-F-something disabled the mousepad PERMANENTLY in one easy mis-type. Not even re-booting could "fix" it (not that it's easy to log in without a mouse), and you needed that one magic keystroke again to get it back. Idiots (no, not the users, Toshiba! ) The users were seriously contemplating scrapping and replacing them. If this had happened Toshiba would have lost a lot of custom because of "crap mousepads" -- maybe elsewhere, they have.