Sets the actions on the `GtkDragSource`.
During a DND operation, the actions are offered to potential drop targets. If actions include
gdk_action_move, you need to listen to the [[email protected]:GtkDragSource:drag-end] signal and handle
delete_data being true.
This function can be called before a drag is started, or in a handler for the [[email protected]:GtkDragSource:prepare]
signal.
| this |
a `GtkDragSource` |
| actions |
the actions to offer |