1. CheckBox Size: I have several checkboxes that are
identical in height and width, and spaced uniformly within
a frame. The actual size of the checkbox "box" varies
slightly from one to the next. The size differences are
small but noticeable. Further the size and "darkness"
(probably change in font size) of the checkmark (when the
box value is true) varies as well, some are smaller
and "light" and some are larger and "dark". I have
fiddled around with heights (making them all one or two
points larger or smaller), locations, etc., but can not
get the boxes to be the same size. What am I doing wrong
here?

2. CheckBox communications: I have several checkboxes in
a frame. I want to limit the user to one selection. Thus
if box 1 is selected (value = True), boxes 2, 3 and 4
should automatically have values = False. How is this
done?