The layer is in the wrong place. Forcing a new layout snaps it to the right place, so it's some problem where the layer position is initially incorrect (or only the widget position is incorrect and it syncs to the layer later).
This is a blocker for turning the new columns on.
*** Bug 131984 has been marked as a duplicate of this bug. ***
Created attachment 229879 [details]
Created attachment 229880 [details]
Comment on attachment 229880 [details]
Your fix is basically just working around the fact that the flags were wrong. This is because some code is missing from FrameView. It's patched for the old columns but not for the new ones. I'll post a revised patch with your test case in a bit.
Created attachment 229884 [details]
Fixed in r167663.