>I have two listbox. The positions are the same for both.
>When one the first one is visible=.F., I cannot click
>to select an item in the one behind which is visible=.T.
>
>Is it a bug?

< SET SWAG ON >
Are you toggling the Visible property of the listboxes of the containers that hold them? If it's only the listbox, then the container is possibly still visible but transparent and it may block your mouse clicks.
< SET SWAG OFF >

HTH.