Comment 36 for bug 35876

"last click was on the panel's menu window, which doesn't exist anymore"

That isn't the way menus work, though; you can see this with the menus of any application. The case you mention in your first footnote is in fact the general case for all menus-- they always give focus back to where it came from. Anyway, we generally try not to have cases where *nothing* has focus. It makes the keyboard rather useless and confuses accessibility.

For what it's worth, if you open the new application with the panel menus, we do know the launch time because of the startup-notification system.

It's an interesting idea to use process creation time as point "A". Note, though, that it's not windows belonging to the same kernel process as such but windows which are marked in X as belonging with one another; you could imagine having one Java virtual machine process for the whole system running several applications.

I will think and confer and consider the other points.