Is there a command line switch for firefox.exe or an "about:" URL that will either force an update check or at least display the Help/About dialog, which checks for updates and tells if you're running the latest version?

One site claimed that the "about:" URL was the same as menu Help -> About, but it's not.

I built a program to automate the updating of various programs on my machine, and most programs have command line tools for checking for updates. Windows update has wuauclt.exe, Java has jucheck.exe. For some applications, I can even automate the interface, but it's difficult in Firefox, because the main window title is unpredictable (it depends on which web page is active), and all Firefox windows seem to use the exact same window class name.