Windiow Background Help!

["u821417" <u821417 alumni nthu edu tw>]

Dear Sir or Madam:

I just have a GTK+2 question. 
I have many buttons on a window. 
They all are with pictures,and what i need is the transparent effect. 

What i am wondering is 
(1)I cannot show the window background picture. 
(2)Widgets cannot overlap! (i.e.,i cannot put image on an image) 

Please show me how to do that. 
Could you please share me the source code? 

Please email to u821417 alumni nthu edu tw 

Thank you very much!