I have created a custom window using slabs (File > Libraries and objects > Save Selection as > Window) (see screen 1)
The window turns out like I want it to - however, the window hole is rectangular, instead of being the same shape of the window. See screen 2 with settings for the window, can't find anywhere to change this. What did I miss in the process?
AC 19 / iMac 2013 3,2 Ghz 12 GB RAM / OS X El Capitan