The majority of sliding screen doors have rollers (wheels) that ride upon a raised track rail and the door itself is merely held onto the track rail with gravity.  Occasionally, there may be some spring-loaded rollers or devices at the top of the screen door to provide additional downward pressure. If the screen keeps popping off the track, it usually needs new rollers.  However, there is another common situation which causes the screen to pop off… even when the rollers are new. The stationary panel of the glass patio door