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>>If it would be the existing form, how should I make it look like a popup?

Create a form that doesn't have the controlbox or title bar, then drop the calendar on it. When you click on your button, create an instance of this form object and calculate it's position (then set the forms top/left properties) and Show() it, and then call the AddDate with any date that may have already been selected. Set the lMultiselect property to True. In your button, bind to the AddDate() method and hide the form when it fires. You can also populate any textbox or anything else at this point with the selected date. Finally, release the hidden form.

At some point I'll probably release my latest version which already does all this. I just haven't had any time to package it all up.