Hello,
I've been working with QCodo for a while and I find it extremely useful and well-designed. Congratulations, you've done a pretty good work :)
My suggestion to make it even better is to add one new property to every QControl: ReadOnly. It would render the value of the control without allowing the user to modify it, and without putting it in grey as Enabled. Also, it could change the way it if showed (the calendar could be rendered to only one label).
Greetings to everybody :)