Comment 35 for bug 278112

I can confirm that the patch Thierry posted does allow the screensaver to start normally. The "lock screen..." checkbox in gnome-screensaver didn't cause any issues here.

However, it still introduces the white screen when switching users with the User Switcher on the panel. Black screen on resume is no longer an issue. Here is a possible solution; I just don't know how to implement it:

If a user wants to "lock screen after switching users" when using the User Switcher applet, why not return to the GDM login screen for the password? The click on "System, Log out, Switch user" approach to switching users seemed to work. So, that could be an easy workaround. If a user doesn't lock their session, then the white screen is not an issue when you return to that session.

Sorry about the repeated misspelling of "Unredirect Fullscreen Windows" in the previous post!