I have tried to place windows in a simple 30' x 40' rectangular structure with 8" exterior walls, 1' thick floor, no interior wall partitions and no roof. I manage to get two finished windows with mullions protruding 1" on exterior and interior walls, create the openings on the interior, then paint Low-E glass on the exterior windows that are flush with the exterior wall. I think, "Success I finally solved that!"

The problem is that after further Orbits and Pans around the model for unrelated tasks, I come back to the window side and find the windows opaque. They are not even uniformly opaque because one will still have Low-E color without transparency and the other will be a shaded rectangle without transparency.

The problems cannot be uniformly resolved. Select one window pane, delete it, close the rectangle and repaint will bring it back to transparent Low-E. I try everything to select/correct the other window pane, but it has been logically reconnected to the wall and every attempt at selection grabs the pane along with the adjacent exterior wall on that side of the building. It does not select the exterior mullion between the pane and wall.

I have begun and abandoned several models because of this difficulty.

I really would appreciate any suggestions.