How can i create a dialog?

[cheerbase]

Just started using NGUI to re-write my ui but this quetion comes to me:
How can i create a dialog? I mean there is a dialog panel. When this panel become visible,every other panel is still visible but the buttons on them won't receive input anymore.
Thank you.

[yuewah]

 you can attach a box collider to the dialog panel that cover the whole screen.