Window holder.

thingiverse

Problem: window that can open but cannot be fixed when partially open. Solution: measure your window, make your own holder. Instructions Usually, there is something that holds the window when it is closed. You should measure all the wanted sizes of your optimal holder - it should nearly-tightly fit on the opening part, and its hook should align with the part you want to use as an anchor. Holder slides vertically, but horizontal shift has to be measured. Make sure the cut is wide enough to actually hold. I printed a few copies of various lengths to be able to have window half-open and one-third-open.