Hey Ingix! Thanks for the feedback. I just updated (v1.4), you can now click the level image or number. ENTER should work if navigating with arrow keys (SPACE should now as well).
Thanks, works like a charm!
New question:
I'm in the early 20's levels were differently colored boxes need to be placed on differently colored targets. Now the targets have letters as well (correspondig to the colors), but the boxes don't. Is there a reason for that? I assmued it was done to possibly compensate for color-blindness, but if the boxes don't have the letters, that makes no sense.