Not the computer program, but equally as frustrating when trying to install!
I decided to install the smallest window first, as it is straight forward and low to the ground. This would be good practice for the massive windows that will fill the walls on the sides of the tiny house.
The back window is 36 inches wide, at least that is what the sticker on it said. So I built the tiny house to have a window frame that is 36 inches wide! When I went to install it, the window didn't fit because it is actually 36.25 inches wide. Oh joy!
I cut 1/4 inch notches into the frame on one side of the house and then began splitting the flat sawn 2x4 with a wood chisel.
After mutilating 1/4 inch off of the the window frame 2x4, the window should now fit in its frame.
With the frame cut out to the appropriate size, the window was able to drop right in, be shimmed to level it, and then screwed into the sheathing and 2x4 frame.
From the inside, an important step can be visualized. The tar paper that was covering the window should be folded into the window and wrapped over the frame. This will help keep that wood from rotting away because of rain water seeping in around the window frame.