Created attachment 255518 [details]
The borders disappear (and probably shouldn't).
I'm hiding the first few comments and making the rest of this bug public.
WFM using Mac trunk.
Mats, are you still seeing this assertion with this testcase?
Created attachment 337294 [details]
The first testcase is WFM too, on Linux. I can reproduce the assertion
with this testcase though.
fixed by bug 460637