How can you set the datetime control to only allow user to pick a valid date from graphic calendar.

As it is, the user has a choice to enter their own date or pick a date.  I know the DateTime control

is not a combobox or else I could add property -style => WS_VISIBLE | 3 | WS_VSCROLL | WS_TABSTOP

to make it prevent the user from keying their own value.