Allow completely different shortcuts in the preferences tabs

[rxhfcy]

Thank you for (almost) fixing #237 (for me).

My particular obscure preference would be to be able to switch between all windows with cmd+tab, and between windows of the
current program with alt+tab...

So if the new vertical tab thingies (in "General") would also allow me to change "Hold (desired-key-here) and press:", I would be able to use a different "hold key" for switching between all windows (cmd) and windows of the current application (alt).

Maybe the attached picture explains better what I mean? Does this make sense to you?

[rxhfcy]

So in my particular case:
"tab number 1" (the first picture) would have cmd+tab switching between all windows, and
"tab number 2" (this second picture) would have alt+tab switching between the active app's windows

[lwouis]

Hey @rxhfcy! That's a totally valid point!

I thought extremely deeply about this, as you may be able to tell by the flexibility of the current tabs UI. While thinking about the problem space, I thought about this too. I decided to not do this extra flexibility because I thought nobody would need it. I was wrong ;p

I'll combine this ticket with #458 which goes even further and provides a whole new mode of interaction with AltTab.

[fortu42]

Hi, I would also like to have cmd-tab and alt-tab options to distinguish between all apps and window apps. For me, those two shortcuts are the more natural ones.
Thank you and keep up the great work.