[Gtk-sharp-list] progress bar not properly updating

[Simon T.]

hi!
i got a little problem with my progressbar, it doesnt update correctly.
i wrote a function, that does some calculation and updates my bar using 
fraction. the function is called on button.clicked event.
first it didnt update at all, then i found a hint in the gtk faq 
(http://www.mhatt.aps.anl.gov/dohn/programming/gtk-2.0/gtk-faq/x561.html), 
so i added while (Gtk.Main.Iteration()); (also triedwhile 
(Gtk.Main.IterationDo(false)); theres no documentation about Gtk.Main in 
monodoc yet).
my bar now updates correctly as long as the mouse is over the ok-button 
which calls the function. if  i move the mouse to somewhere else it 
stops updating until the calculation is done.
is this a bug, or is it suposed to bahave like that? how can i get it to 
update even if the button looses focus?
(i also tried to call the function on button.released, didnt help, also 
tried to call that gtk.main.iteration on button.left/button.released, 
problem still there.)
thanks in advance
Simon

btw. im using  mono0.31 and gtk#0.18