I can confirm this bug.
Oddly the screensaver does not turn on , but the screen is put to sleep at the
set time in gpm preferences.
** Also affects: gnome-screensaver (Ubuntu)
Importance: Undecided
Status: New
** Changed in: gnome-screensaver (Ubuntu)
Importance: Undecided = Low
*** This bug is a duplicate of bug 49579 ***
https://bugs.launchpad.net/bugs/49579
** This bug has been marked a duplicate of bug 49579
screen doesn't lock when panel menu is open
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Open menus block the screensaver, and then the screensaver kicks in when the
menu is dismissed
