Thanks for your suggestions guys!
But usually I like to build the engine without the need to constantly push sprites out of backdrops they're not supposed to overlap. And it works, but only without TimeDelta.
Doppel's example works sometimes. But most of the time the detector and the player sit on top of the ground. Which is what the event actually does, since you're pushing the movers family out of solid sprites when the detector overlaps.
And if I go by logic the condition should be with the player that overlaps. Which is what deadeye did, but strangely, like cecil said, although the events seem right it still overlaps.
EDIT: I guess deadeye is right. When I add an event
player overlaps solid -> close application
it doesn't quit the app when I just let it drop on the top, although it visually overlaps. But when I move it in sidewards, it ends the application.