I'll follow you to this post then..
I would correct the HTML at the beginning (in particular, to prevent IE dropping into quirks mode) so that it can be tested in all browsers:
Code:
<!DOCTYPE html>
<html>
<head>
<title> CBox/RBtn Tests </title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
Just my personal opinion/
preference but I would return the value
false rather than
null. I might use null if a function is expected to return an object.
Seems to work well. Again, just my personal opinion

, but I would prefer to use separate functions. I think these are trying to do too much, and if I look at this again in a couple of months I'll need to remind myself of what the functions do. Of course, function documentation (docstrings) would help with this.