Setting Sat in QColorDialog will overwrite alpha values

When using QColorDialog::getColor(Qt::white,0,"",QColorDialog::ShowAlphaChannel) to get a color with alpha channel, if you first change the alpha value to 100, then change the saturation
to 100, click on OK, you will get:

QColor(ARGB 1, 0.392157, 0.392157, 0.392157)

in which the alpha value is 1, not 0.39.