`!tkinter.dnd` --- Drag and drop support

Source code: Lib/tkinter/dnd.py

[!NOTE] This is experimental and due to be deprecated when it is replaced with the Tk DND.

The !tkinter.dnd module provides drag-and-drop support for objects within a single application, within the same window or between windows. To enable an object to be dragged, you must create an event binding for it that starts the drag-and-drop process. Typically, you bind a ButtonPress event to a callback function that you write (see Bindings-and-Events). The function should call dnd_start, where source is the object to be dragged, and event is the event that invoked the call (the argument to your callback function).

Selection of a target object occurs as follows:

1. Top-down search of the area under the mouse for a target widget:
   • the target widget should have a callable dnd_accept attribute;
   • if dnd_accept is not present or returns None, the search moves to the parent widget;
   • if no target widget is found, the target object is None.
2. Call to <old_target>.dnd_leave(source, event).
3. Call to <new_target>.dnd_enter(source, event).
4. Call to <target>.dnd_commit(source, event) to notify of the drop.
5. Call to <source>.dnd_end(target, event) to signal the end of drag-and-drop.