tiled, partial transparent background

[Uwe Zeisberger <zeisberg informatik uni-freiburg de>]

Hello,

with gdk_window_set_back_pixmap I can set a tiled background pixmap
and
with gtk_widget_shape_combine_mask I can make my background transparent.

But making the background transparent works only for non-tiled
background. (Else only the upper right tile is shown.) 

Is there a simpler way than build a greater bitmap and then use
gtk_widget_shape_combine_mask to set the background to an tiled pixmap
with transparent areas?

Thanks for you help
Uwe

-- 
Uwe Zeisberger

primes where sieve (p:xs) = [ x | x<-xs, x `rem` p /= 0 ]; \
primes = map head (iterate sieve [2..])