Rubik is a great theme, and I understand the space-saving benefits of the pop-ups, but in practice they make the theme unusable for me. My problem is that many field descriptions can contain really critical information, and I feel that the pop-ups make that information too hard to see.
I'm proposing that this feature be made optional. The pop-ups would still be enabled by default, but it would be possible to switch them off and display the descriptions inline, if people wished to do that.
(For cross-referencing, this is related to; however that was raised for 6.x-3.x, and I didn't want to change those versions).