'Set the orientation of the GradientEditorItem.
**Arguments:**
orientation     Options are: \'left\', \'right\', \'top\', \'bottom\'
The orientation option specifies which side of the gradient the
ticks are on, as well as whether the gradient is vertical (\'right\'
and \'left\') or horizontal (\'top\' and \'bottom\').'

def setOrientation(self, orientation):

    TickSliderItem.setOrientation(self, orientation)
    self.translate(0, self.rectSize)
