Well QItemDelegate::drawBackground() is pointless as there is a bug in Qt-this function has been forgotten to be declared as virtual :/
About your code,I'd write it like:
Qt Code: 
  1. if(role == Qt::BackgroundRole && index.isValid())
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but even without this 'purism' it seems to be OK.For the test,screw up the gradient and return a simple QColor to see if it works.