Thank for ur quick reply zen,

i need further clarification...

I have a QDialog.ui ...in that stylesheet property for the QFrame i was set

Qt Code: 
  2. {
  3.     background-image: url(:/images/messagebox.png) no-repeat;
  4. }
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and in my QDialog constructor

Qt Code: 
  1. QPixmap pixmap(":/images/messagebox.png");
  2.  
  3.     ui->frame->setMask(pixmap.mask());
  4.     QRegion reg(frameGeometry());
  5.     reg-=QRegion(geometry());
  6.     reg+=childrenRegion();
  7.     setMask(reg);
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but i got an error

dialog.cpp: In constructor ‘Dialog:ialog(QWidget*)’:
dialog.cpp:12: error: invalid use of incomplete type ‘struct QBitmap’
/opt/qtsdk-2010.05/qt/include/QtGui/qwindowdefs.h:77: error: forward declaration of ‘struct QBitmap’
make: *** [dialog.o] Error 1