When changing viewports, compiz should always focus the top window on the new viewport

[quequotion]

This is a feature request as much as a bug report.

Compiz should update window focus when changing viewports.

If the new viewport has one or more visible windows, the top level window should be given focus.

If the new viewport has no visible windows, all windows shoud be unfocused.

As it is, compiz often keeps focus on a window from a previous viewport. This is really dangerous, because a user may attempt to interact with a window they can see and not be aware that they are still interacting with a window they can no longer see. An observant user may notice the mouse cursor responding to the previous window (pointer changes to typing cursor, etc according to layout of window on previous desktop), but it's also likely they may think the visible application's window is broken (doesn't appear to respond to interaction, apparently wrong cursors in wrong places).

I am also marking this as a security vulnerability, since it is possible that, while blindly interacting with a window on the previous viewport, a user may inadvertently compromise themselves.

I'm not sure if compiz has always had this problem, but it is a longstanding issue. I have experienced it with multiple versions of compiz across multiple linux distributions, including several releases of Ubuntu.