Fixes #31 for 1.2.12 (I guess it's time for 1.2.13)

Removed nested display lists from screen renderer. It seems to work.
I think it should end up in v1.2_backports branch but I don't know how to tell that to Github. That said, you might have to merge it manually into that new branch. This commit is already branched from v1.2.12 so nothing should go wrong.