'Passing None means any key, or any modifier'

def ungrab_button(self, button, modifiers):

    if (button is None):
        button = xcffib.xproto.Atom.Any
    if (modifiers is None):
        modifiers = xcffib.xproto.ModMask.Any
    self.conn.conn.core.UngrabButton(button, self.wid, modifiers)
