QPalette in rgb

[tommy]

This is how I change the backround or my QLabel

QPalette Pal2(pixmapLabel->palette()); 
          Pal2.setColor(QPalette::Window, Qt::gray);
          pixmapLabel->setAutoFillBackground(true); 
          pixmapLabel->setPalette(Pal2);

QPalette Pal2(pixmapLabel->palette()); 
          Pal2.setColor(QPalette::Window, Qt::gray);
          pixmapLabel->setAutoFillBackground(true); 
          pixmapLabel->setPalette(Pal2);

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I would now like to change the background color to rgb color where I replace "Qt::gray" with RGB numbers. How do I do that?
So far I've tried this.

Pal2.setColor(QPalette::Window, QColor::rgb(150,150,150));

Pal2.setColor(QPalette::Window, QColor::rgb(150,150,150));

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and

Pal2.setColor(QPalette::Window, QRgb::rgb(150,150,150));

Pal2.setColor(QPalette::Window, QRgb::rgb(150,150,150));

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but neither work.