Expected behavior: If the ESC key is pressed while a file is dragged the drag operation is aborted.

Problem: In some cases this does not happen: The ESC key closes the currently focused modal dialog, which was also setup as drop target. Drag operation is not aborted, which leads to a crash as soon as another widget is hovered.

How to reproduce (on macOS):

1. build + start the attached app
2. start app, click on button -> DragDropDialog opens
3. click on Finder window -> DragDropDialog gets inactive
4. from Finder, drag (but don't drop!) a file over the DragDropDialog
5. (don't drop!) wait a second until the focus is automatically moved to the DragDropDialog, i.e. it gets active
6. (don't drop!) press ESC -> the DragDropDialog is closed
7. (don't drop!) move the mouse cursor over the MainWindow -> the app crashes immediately; if the mouse cursor was already over the MainWindow, the crash happens as soon as ESC is pressed and the modal dialog is closed