[gtkmm] basic reordering with dnd

[Maurizio Umberto Puxeddu <mauriziopuxeddu yahoo it>]

Hello.

Gtkmm tutorial says that the treestore example should explain how the
basic dnd reordering work with gtkmm.
The problem is that I cannot do any dnd using that example on my system
even if set_reorderable() is called.

Any suggestion?

Maurizio Umberto Puxeddu.