just a thought, but what if you started with D3 Sliding 01 23 > moprh>rotate... save as window ?
It works ok. But be sure you size the door properly first, and configure the fame size and other options like the Casing first . Also, since it will be missing the casing on the side( bottom of the door) you can split the window/door/morph - mirror a copy for the other half, then use the Union morph function to make it all one unit. It will look something like this