I'm running KDE 4.2.2 on Fedora 10.

I've been having trouble with the Application Launcher. When I click on the icon on the panel, the launcher menu pops up, but there is a small gap, maybe 1 pixel between the top of the panel/launcher button and the menu. The problem with this is that when I move the mouse upward from the menu to the window, the window in the background gets focus, and the menu disappears.

If I shoot the mouse up really fast, this does not happen, but it's not a reliable way to get to the menu.

Is there any way to fix this?

I suppose you're using the "focus follows the mouse" option?

If that's the case, just put a small delay for it ~ 250ms (System Settings -> Window Behaviour -> Focus -> Delay focus by)

Focus delay of one fourth of a second is not really noticeable while you work, and is sufficient enough to solve your problem.

I suppose this is a reasonable workaround.

This looks like a real bug to me though. If it is, how do I report it?

It is expected behaviour.

When focus follows the mouse, another window gets the focus.
Menu is set to close on focus lost.

As simple as that.

If you're persistent to file a bug for it, just go to bugs.kde.org

After some hunting, this was apparently a known bug https://bugs.kde.org/show_bug.cgi?id=180968 . I guess at some point I'll have a fix for it.

The policy of hiding the menu when focus is lost doesn't make sense from a usability standpoint.