Window switch notification for plasma applets

[Andriy Rysin]

Currently the keyboard layout switcher (when in per-Window or per-Application mode)
  ignores the desktop when it becomes the active window. This was done intentionally so that when keyboard layout applet (on the desktop) is clicked it would change the current (or technically previous) active window's layout instead of the desktop's one. Though it seems that as people use more applets which take the keyboard input this becomes the problem (e.g.https://bugs.kde.org/show_bug.cgi?id=269661).
I guess I could treat the desktop window as a separate layout container and come up with some workaround to allow layout switcher applet to skip the active window switch if it's been clicked on desktop. But if people use more applets it might make sense to be able to keep layouts per applets as well as per top-level windows.
So the question is whether there's a way to tell "active/focused" applet and get notified on switch?

Thanks
Andriy