hi
for setting a image using stylesheet
Qt Code:
  1. t->setStyleSheet("background-image: url(computer.gif)");
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for setting a transparent in a stylesheet
Qt Code:
  1. background-color: qlineargradient(x1: 0, y1: 0, x2: 0, y2: 1, stop: 0 #6666FF, stop: 0.7 #99CCFF , stop: 1 #CCCCFF);
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work it around, u may find a solution. (im not sure ,it helps or not)
hope it helps

Bala