Emitted on the drop site when a drop operation is about to begin.
If the drop is not accepted, %FALSE will be returned and the drop target
will ignore the drop. If %TRUE is returned, the drop is accepted for now
but may be rejected later via a call to [method@Gtk.DropTargetAsync.reject_drop]
or ultimately by returning %FALSE from a [signal@Gtk.DropTargetAsync::drop]
handler.
The default handler for this signal decides whether to accept the drop
based on the formats provided by the @drop.
If the decision whether the drop will be accepted or rejected needs
further processing, such as inspecting the data, this function should
return %TRUE and proceed as is @drop was accepted and if it decides to
reject the drop later, it should call [method@Gtk.DropTargetAsync.reject_drop].
Emitted on the drop site when a drop operation is about to begin.
If the drop is not accepted, %FALSE will be returned and the drop target will ignore the drop. If %TRUE is returned, the drop is accepted for now but may be rejected later via a call to [method@Gtk.DropTargetAsync.reject_drop] or ultimately by returning %FALSE from a [signal@Gtk.DropTargetAsync::drop] handler.
The default handler for this signal decides whether to accept the drop based on the formats provided by the @drop.
If the decision whether the drop will be accepted or rejected needs further processing, such as inspecting the data, this function should return %TRUE and proceed as is @drop was accepted and if it decides to reject the drop later, it should call [method@Gtk.DropTargetAsync.reject_drop].