modal windows ?

[Mario Motta <mmotta guest net>]

hello,
perhaps an old question, but someone could answer to me:
- how can make a child window a modal one ?
- in other word if i make a child dialog window from inside a window how
can make the 'parent' deactivated (no receive signals nor events) so i
can interrupt the user activity until in this task pushes an OK button ?
- how can make the dialog stays "always on top" ?

thanks a lot.