DndEvent Drop not registered

[tfachmann]

I try to implement a drag and drop functionality for winit (compare tfachmann/winit@761d1bb).

In my initial tests I realized, that DndEvent::Drop is never emitted. DndEvent::{Enter, Motion, Leave} seem to be working fine. Here some output of the DndEvent while entering and dropping a file:

Enter { offer: Some(DataOffer { offer: wl_data_offer@4278190080, inner: Mutex { data: Inner { mime_types: ["text/uri-list", "DELETE"], actions: Copy | Move, current_action: None, serial: 0 }, poisoned: false, .. } }), serial: 53571, surface: wl_surface@21, x: 337.21484375, y: 694.51953125 }
Motion { offer: Some(DataOffer { offer: wl_data_offer@4278190080, inner: Mutex { data: Inner { mime_types: ["text/uri-list", "DELETE"], actions: Copy | Move, current_action: None, serial: 0 }, poisoned: false, .. } }), time: 21857971, x: 337.21484375, y: 694.51953125 }
Motion { offer: Some(DataOffer { offer: wl_data_offer@4278190080, inner: Mutex { data: Inner { mime_types: ["text/uri-list", "DELETE"], actions: Copy | Move, current_action: None, serial: 0 }, poisoned: false, .. } }), time: 21857980, x: 338.21484375, y: 694.51953125 }
[...]
Motion { offer: Some(DataOffer { offer: wl_data_offer@4278190080, inner: Mutex { data: Inner { mime_types: ["text/uri-list", "DELETE"], actions: Copy | Move, current_action: None, serial: 0 }, poisoned: false, .. } }), time: 21858069, x: 342.1875, y: 690.546875 }
Motion { offer: Some(DataOffer { offer: wl_data_offer@4278190080, inner: Mutex { data: Inner { mime_types: ["text/uri-list", "DELETE"], actions: Copy | Move, current_action: None, serial: 0 }, poisoned: false, .. } }), time: 21858076, x: 342.1875, y: 689.546875 }
Motion { offer: Some(DataOffer { offer: wl_data_offer@4278190080, inner: Mutex { data: Inner { mime_types: ["text/uri-list", "DELETE"], actions: Copy | Move, current_action: None, serial: 0 }, poisoned: false, .. } }), time: 21858089, x: 343.1875, y: 689.546875 }
Motion { offer: Some(DataOffer { offer: wl_data_offer@4278190080, inner: Mutex { data: Inner { mime_types: ["text/uri-list", "DELETE"], actions: Copy | Move, current_action: None, serial: 0 }, poisoned: false, .. } }), time: 21858093, x: 343.1875, y: 688.546875 }
Leave

Also: Is it possible to access the file path?