I don’t think it can be regarded as a bug in ArgyllCMS - it seems to be a characteristic or bug in X11. “dispwin -X” is an experimental feature, and there are probably better ways of achieving the same functionality along the lines of triggering a script on display change using udev, and then have it call the new “displwin -x” option. Perhaps someone can figure out how to do that, and I can add a “how to” to the ArgyllCMS Linux install notes.