[gtkmm] Windows on top of fullscreened windows

[Igor Gorbounov <igorbounov topazelectro ru>]

Hi, All!
There is hopefully a misunderstanding (I misunderstand) in a windows 
behaviour.
When a daughter window (a normal Gtk::Window) is created and showed as 
transient
for a parent window, it stayes ok upon the parent window. This seems to 
be in accordance
with gtk+ and gtkmm documentations.
But when the parent window is fullscreened, those daughter windows
hide themselves under their parent window, whenever you try to touch 
them. Isn't it weird?
And only if the daughter window is created as a dialog window (in 
addition to "transient_for")
it stays upon their parent window. What's so special in dialog windows? 
May be
there is a way for using this unknown feature with normal (gtk_windows) 
windows?
Those dialog windows have some annoying features...
   Igor Gorbounov