public class DropTargetAsync : EventController
`GtkDropTargetAsync` is an event controller to receive Drag-and-Drop operations, asynchronously.
It is the more complete but also more complex method of handling drop operations compared to [class@Gtk.DropTarget], and you should only use it if `GtkDropTarget` doesn't provide all the features you need.
To use a `GtkDropTargetAsync` to receive drops on a widget, you create a `GtkDropTargetAsync` object, configure which data formats and actions you support, connect to its signals, and then attach it to the widget with [method@Gtk.Widget.add_controller].
During a drag operation, the first signal that a `GtkDropTargetAsync` emits is [signal@Gtk.DropTargetAsync:
], which is meant to determine whether the target is a possible drop site for the ongoing drop. The default handler for the
accept signal accepts the drop if it finds a compatible data format and an
action that is supported on both sides.
If it is, and the widget becomes a target, you will receive a [signal@Gtk.DropTargetAsync:
followed by [signal@Gtk.DropTargetAsync:
GtkDropTargetAsync:drag-motion] signals as the pointer moves, optionally a [
GtkDropTargetAsync:drop] signal when a drop happens, and finally a [signal@Gtk.DropTargetAsync:
GtkDropTargetAsync:drag-leave] signal when the pointer moves off the widget.
The drag_enter and drag_motion handler return a `GdkDragAction` to update the status of the ongoing operation. The drop handler should decide if it ultimately accepts the drop and if it does, it should initiate the data transfer and finish the operation by calling [method@Gdk.Drop.finish].
Between the drag_enter and drag_leave signals the widget is a current drop target, and will receive the gtk_state_flag_drop_active state, which can be used by themes to style the widget as a drop target.