'Explicitly determine which ticks to display.
This overrides the behavior specified by tickSpacing(), tickValues(), and tickStrings()
The format for *ticks* looks like::
[ (majorTickValue1, majorTickString1), (majorTickValue2, majorTickString2), ... ],
[ (minorTickValue1, minorTickString1), (minorTickValue2, minorTickString2), ... ],
If *ticks* is None, then the default tick system will be used instead.'

def setTicks(self, ticks):

    self._tickLevels = ticks
    self.picture = None
    self.update()
