'Saves a screen capture of the plot window to an
image file.
If outfile is given, it can either be a path
or a file object. Otherwise a png image will
be saved to the current working directory.
If the format is omitted, it is determined from
the filename extension.'

def saveimage(self, outfile=None, format='', size=(600, 500)):

    self._screenshot.save(outfile, format, size)
