Resizing or moving a window => focus change ?

[Mario Motta <mmotta guest net>]

hello to all,
i'm a novice in Gtk+ (XWindow also) but i could'nt explay this
behaviour:
- if you move and/or resize an already focused window this still receive
a "focus change" event. I tried this in different wm's (fvwm, fvwm-95,
WindowMaker, olvwm..) and all display same behaviour, in some cases it's
enough to click on upper bar to cause a "focus change" event:
(GdkFocusEvent->type == 12 and GdkFocusEvent->in == 1).
I'm missing something ? ...