I also really liked that feature in windows 7! Unfortunately, there is no way to reproduce such behavior in GridMove.
Honestly, I think it might be possible to achieve, however it involves GridMove doing much more complex stuff than it already does.
Thus, even though I'd like to see that in GridMove, I'll probably never get to do it. I'd really encourage someone else to try to implement it, and I'd provide all the help I can!