keep in mind that while those are notables from 4.2.0 the list of changes since the last screen release is actually huge. vert splits for example was added in 2009, layouts in 2010. they really should have made a few releases in between.

you might find some interesting patches to your use cases in here:

http://git.savannah.gnu.org/cgit/screen.git/log/?h=screen-v4

given that it takes most distros a fairly long time to adopt new software I would say in a sense the screen devs kind of shot themselves in the legs in a way by not making any intermediary releases.

I guess in a way that's a lesson to us all on how you shouldn't act if you want to keep your customer base.