public void set_icon_drag_source (EntryIconPosition icon_pos, TargetList target_list, DragAction actions)
Sets up the icon at the given position so that GTK+ will start a drag operation when the user clicks and drags the icon.
To handle the drag operation, you need to connect to the usual drag_data_get (or possibly drag_data_delete) signal, and use get_current_icon_drag_source in your signal handler to find out if the drag was started from an icon.
By default, GTK+ uses the icon as the drag icon. You can use the drag_begin signal to set a different icon. Note that you have to use connect_after to ensure that your signal handler gets executed after the default handler.
the targets (data formats) in which the data can be provided
a bitmask of the allowed drag actions