Gable End Double Roof Match Window

[Ed Orum]

I am using V10.8a.
I have a cabin and need to make a gable end window where both sides of the top match the roof.
I can convert a fixed glass windowto match one side of the roof with the "match roof" in the shape box. Next I would like to reflect that so the top of the window is a triangle with both angles matching the roof. Roof pitch is same on both sides.

Thanks in advance,

Ed Orum