Hello,
in past I used some kind of layout that kept an "active rectangle", and you could insert a new widget in the layout splitting that "active rectangle" in half, both vertically or horizontally. This allowed to insert widget quickly just specifying the orientation.

Something like this
layout_splitter.png

the "active rectangle" is the last inserted one, which starts from one.
I'm sure I found something like this time (years?) ago, but I can't find it again...
I'm not even sure it was a qt feature :S

Thanks in advance
~Aki