When we were renovating this old detached garage to be my art studio, we built French doors into it, to get all the natural light possible. Then Ralph came along. And he is very territorial. Someone driving by on a bike? He barks. Squirrel? He barks. A house guest who leaves the house? He barks once he sees them out the window.
So the French doors are covered by Roman shades. But Ralph seems to have made adjustments to them accordingly, in order to bark at the neighborhood cat.