tkdnd is an extension that adds native drag & drop capabilities to the
tk toolkit. It can be used with any tk version equal or greater to 8.4
and currently only the UNIX (X-Windows) and Microsoft Windows operating
systems are supported. Under Unix the drag & drop protocol in use is the
XDND protocol version 4 (also used by the QT toolkit, KDE & GNOME
Desktops).

WWW: http://www.iit.demokritos.gr/~petasis/Tcl/tkDND/tkDND.html