There’s already a file_drag_enter event
Viewing post in File Dragger and File Dropper for GameMaker comments
I appreciate the response, but from what I can tell file_drag_enter doesn't return the filepath. The only event I can see from your docs that returns filepaths is the file_drop event. If I try to use the filepath it returns as undefined.
I hadn't considered how it would be handled if multiple files are being held, though; I can understand if that complicates things too much.
Added those, and you may decide for yourself what status should be shown if only some of the dragged items are acceptable.