'Instruct the window manager that this widget shall only be
resized on grid boundaries. WIDTHINC and HEIGHTINC are the width and
height of a grid unit in pixels. BASEWIDTH and BASEHEIGHT are the
number of grid units requested in Tk_GeometryRequest.'

def wm_grid(self, baseWidth=None, baseHeight=None, widthInc=None, heightInc=None):

    return self._getints(self.tk.call('wm', 'grid', self._w, baseWidth, baseHeight, widthInc, heightInc))
