This is really, already not bad !
I also liked very much the shift button, but it should be automatically unshifted after another left click is detected.
(Or after a certain number of seconds)
Otherwise if shift is held all the time the mouse wheel is not working any more.
Sometimes I was unsure which button was in use, a visual help would be good like inverseing the colour of the button.
I have to try more with several programs and see how it is reacting/working then.
Complex programs like Photoshop was such, are a very hard to handle in general with all the available programs.
All in all already a very nice approach !
I really liked the idea that it disappears and reappears, this is very nice thinking.
The best way to figure out what can be changed or be different is to try it,
I mean, try only to do all the things you usually do without touching the keyboard or the mouse buttons.
When ever you reach for the keyboard, then there is a need to adapt the program so it can be done without it.
Things like: hold this or that key and click the left mouse button are is simply impossible,
but as you will experience those combinations will show up more often than you wish.
Maybe one or two buttons, that can be freely assigned to whatever might help.
Great work so far !
Thanks a lot,