I am using dual head set-up having two monitors utilizing ATI's Big Desktop technology (Big Desktop = TwinView = Xinerama). Though it's a hack, somehow applications are aware of it. E.g. they maximize windows correctly.

What bothers me that new windows are constantly opened on the wrong monitor. This goes for new application launches, etc. Sometimes they are opened on the monitor where I launch application, click button, etc. but this is a rare case. I am not following the pattern which defines the monitor for a new window.

This could be easily cured: Open all new windows on the monitor where the mouse cursor is, unless specified otherwise. This way we know that user is looking at the position of a new window and new windows don't go unspotted.





Other information:
This is extremely annoying for keyring dialogs and such windows which should be modal. When these dialogs go unspotted after opened on the wrong monitor, the user  thinks that there is something wrong with his/her applications when it behaves really strangely.

For example, opening a keyring dialog for Samba connection on the wrong monitor allows Nautilus to continue working, but makes Nautilus to look like it's waiting for a network connection forever (network has problems).