Not sure if this has been suggested but..

'kay... a couple of suggestions here.

1) User-definable keys, like... *frowns* the best suggestion I have for an example is Textpad, where you can reassign keys to program functions. Not sure how useful that would be, but it's a suggestion.

2) This is the one I'd like to see more... a definable key-combination to scroll through worlds w/out using the Activity Bar or alt+w, <number> combinations... something like, ctrl+shift+up arrow/down arrow to move through connected worlds; additionally, in order to help identify which world is connected, some sort of marker on the activity bar (like, a black square surrounding the number of the currently active world,) that will move with the selection process (so that selection isn't a guessing game of sorts. ;)

1. The idea of customisable keystrokes is definitely on the list of things-to-do.

2. You can scroll through worlds using the standard Windows "switch window" keystroke: Ctrl+Tab

The only problem is knowing which is the active window. On your suggestion I have added to the next version, 3.10, a tick that will appear in the activity list next to the world that is currently active. For now, you can tell by looking at the title bar - hopefully your world name is there, and you can tell which world is which.

Additionally to that, ctrl-shift-tab goes backwards through the windows.