This patch corrects a reparenting bug in the *paned widgets.

In 0.99.3 a paned widget does have a realize function, but no
widget->window. The realize function is used to create the "grip"
of the paned widget (this, in particular, allow the cursor change...).
Dispite this window creation, a paned widget is a NO_WINDOW widget
(as it doesn't have a widget->window).

Now, if you reparent a paned widget, it will reparent correctly,
except the "grip" which will still keep its old parent window.

I fixed this by adding a widget->window to the paned widget (which
is logical for every widget with a *_realize function anyway).
You can now consider that gtkpaned, gtkhpaned, gtkvpaned widgets
are not NO_WINDOW anymore.



The patch is against 0.99.3.

Patrice.