'Set the \'target\' size for this Dock.
The actual size will be determined by comparing this Dock\'s
stretch value to the rest of the docks it shares space with.'

def setStretch(self, x=None, y=None):

    if (x is None):
        x = 0
    if (y is None):
        y = 0
    self._stretch = (x, y)
    self.sigStretchChanged.emit()
