> it sills maddens me there's no somewhat universal tab-entry in OSes like we have with enter

That's a good point!

Were it up to me, I'd probably say something like: Ctrl+`, or maybe ` followed by escape, or something like that. Maybe one of the function keys? Eh...most if not all of those have been hijacked to mean various inane and stupid things too. :/

Hmm...oh! How about: Caps Lock+Shift ? I'm using an ergonomic keyboard, but I think the button press would still work pretty easily. I assume most styles of keyboard would have both, so it wouldn't lock people out if they are writing in a different language, either.