If you want to add a real Windows CheckBox control to the calendar, it is not possible. You can do it only by positioning the check box on top of the calendar at the appropriate location in order to give the impression that the check box is part of the calendar.

However, you can achieve check box functionality inside the calendar control by using custom drawing and proper event handling. Check the MultipleResourceSelection sample - it illustrates how to do it. This sample custom-draws small check box-like components inside the row headers of a Resource view. The user can then click these components in order to change their state and trigger special functionality.

I hope this helps.

Regards,
Meppy