[24.5.1] Inquiry request about emacs focus hooks

[Skorzhinskiy Mikhail]

I'm heavy user of powerline (https://github.com/milkypostman/powerline)
package and experience troubles with it. This package provides
possibility to change color of the modeline depending on the focus. All
inactive frames become gray except the focused one.

But when I tried to use this feature with two frames, I've got this:
http://i.imgur.com/ke3t4Gc.gif. In short, the powerline package says that
previously selected frame is active, despite the fact that it is not.

I've tried to find out why it is happening and discovered that powerline
package have one function that selects active window by calling
(frame-selected-window), and this function called as a handler of hooks
(frame-in-hook), (frame-out-hook) and
(window-configuration-change-hook). And in this handlers the
(frame-selected-window) still points to the previously selected window,
therefore if you wait some time and call (frame-selected-window) once
again you will get the correct value.

So the question is: is it a bug or such behavior is normal? And if it
normal, how can I find out what frame is selected in (frame-in-hook)?

-- 
best regards,
Skorzhinskiy Mikhail