I think I may have hit upon the perfect way to adjust the opening in the vertical sliding windows that some of us have. As you may know, the window is either fully open or closed with no provision for mid-way adjustment. While I haven't tried it yet, I think a simple suction cup stuck on the bottom, fixed pane would serve as an admirable and infinitely adjustable stop for the top, sliding pane. I'm on my way to the suction cup store.......
Al
Al