fail to lock screen if gnome menu is active

I am testing new Ubuntu 10.04 and notice that some times my laptop didn't lock the screen if left idle. Today I managed to replicate the problem. Here are the steps:

1. Open the "Screensaver Preferences" window ( "System" > "Preferences" > "Screensaver" )
2. Set "Regard the computer as idle after:" 1 minute (I didn't want to wait to much. The problem will happen even if the time is set to default value of 5min.) Also make sure that "Activate screensaver when computer is idle' and 'Lock screen when screensaver is actrive" are checked.
3. Press 'Close' to close "Screensaver Preferences" window.
4. Verify that screeensaver works by waiting 1 min. The screensaver should get activated. When you move the mouse or press any key you should be ask for password in order to unlock the screen.
5. Now click on "Application" from the gnome menu bar. This will open the submenu. Leave the submenu open and wait for 2 min. You will notice that screensaver will not get activated and as result the screen will not get locked after the set idle time elapse. (I was able to replicate this with any pop-up menu from the top panel like Network Manager right-click menu and etc.)
6. After the idle time elapses you can click on any item from the menu and it will start the program, but shortly after that the screensaver finally gets activated and the screen gets locked.

I consider this to be a security problem because if you have sensitive document open it will remain visible on the screen.

What I can do more in order to resolve the issue?

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: gnome (not installed)
ProcVersionSignature: Ubuntu 2.6.32-20.30-generic 2.6.32.11+drm33.2
Uname: Linux 2.6.32-20-generic i686
Architecture: i386
Date: Tue Apr 13 09:06:33 2010
InstallationMedia: Ubuntu 10.04 "Lucid Lynx" - Beta i386 (20100318)
ProcEnviron:
 LANG=en_US.utf8
 SHELL=/bin/bash
SourcePackage: meta-gnome2