The Control-U thing toggles from one of many views, those with large collections find it faster than anything currently available that is menu driven, but not as useful as a dedicated button. I've asked for this many times, but it would be great to have the ability to add these views separately in the toolbar editor, that way the interface can stay squeaky clean for those that like mystery, and for people like me that deal with mystery 89% of the day and are pretty much over it by the time it is time to relax, it would be great to just click and go where you want.
The real driver for me is I change my view many dozens of times daily as I use MC, dedicated buttons would be very welcome, or separate key commands, something, anything...it really is the only thing that bugs me about MC other than the ultimate problem solving detail / thumbnail fantasy...
Maybe Control-Me would be a better key command?