(a) add a check in PreviewWindow to take care of a null pointer exception that would occasionally occur just after popping up a plot preview window, resulting in all data streams to stop sending data to CT
(b) fix minor problem with the size of webcam preview window (inadvertent side affect of the prior change to webcam logic, the webcam preview window would grow in size every time the preview windows were popped down and then brought back up again)
(a) add a check in PreviewWindow to take care of a null pointer exception that would occasionally occur just after popping up a plot preview window, resulting in all data streams to stop sending data to CT
(b) fix minor problem with the size of webcam preview window (inadvertent side affect of the prior change to webcam logic, the webcam preview window would grow in size every time the preview windows were popped down and then brought back up again)