Comment 6 for bug 855042

    def check_composite(self):
        '''Check for a composite-enabling X.org driver.

        If one is available and not installed, offer to install it and return
        True if installation succeeded. Otherwise return False.
        '''

        h_id = self.backend().check_composite()

        if h_id:
            self.set_handler_enable(h_id, 'enable', True)
            return bool(self.backend().handler_info(h_id)['enabled'])

        self.error_msg(self._('There is no available graphics driver for your system which supports the composite extension, or the current one already supports it.'))
        return False

Looks like this always asks for confirmation regardless?