Paints the slider button using painter p with size, a colorgroup and position given by r . Reimplement this function to change the look of the slider button. Setting the colorgroup is useful to reuse the code to draw a mask if the slider supports transparceny. Implements the virtual QRangeControl function. Reimplemented from QRangeControl.
Handles resize events for the slider.
Reimplemented from QWidget. Sets the background color to the mid color for Motif style sliders. This is a value interval, not a pixel interval. Both The initial value is NoMarks. Reimplemented from QWidget.