g_idle_add and threads

[Andrey Dubravin <daa84 inbox ru>]

Hello,

i write mulit-threaded gtk+ application and make all the GTK+
calls in a single thread using g_idle_add_full. 

At GTK-FAQ i read that In such program i should still call
g_threads_init(), but don't need to call gdk_threads_init(),
gkd_threads_enter(), and gdk_threads_leave(). 

And the question is: It is need to call gdk_threads_enter/leave inside
idle handler if i use gdk_threads_init function? (why?)
Does gtk run some other threads with gtk calls in it?

And second question:
Does gtk_icon_theme_lookup_icon (gdk_pixbuf_composite_color) thread
safe?
Can i call this function in over thread without gdk_threads_enter? 

Thanks!

Sorry for my bad english:(
-- 
Dubravin Andrey