QwtDial - multiple Background color

[Maximus2]

Hi guys,

Here is my current QwtDial
Here is what I would like (forgive my painting skills)

I can put one color that fit the circle totally but I'm failing at using multiple color at the same time.

QPalette palette;
palette.setColor( QPalette::WindowText, QColor(89, 130, 67) );   //GREEN 90-270
palette.setColor( QPalette::WindowText, QColor(35, 53, 216) );   //BLUE 0-90
palette.setColor( QPalette::WindowText, QColor(168, 18, 18) );   //RED 270-360

QPalette palette;
palette.setColor( QPalette::WindowText, QColor(89, 130, 67) );   //GREEN 90-270
palette.setColor( QPalette::WindowText, QColor(35, 53, 216) );   //BLUE 0-90
palette.setColor( QPalette::WindowText, QColor(168, 18, 18) );   //RED 270-360

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I'm using the DialBox example modified for my need found in the qwt/examples
Thanks if you can give a hand to a Qwt newbie!