Editing Date property in PropertyGrid

Hi all,

I have a Property Grid where user needs to assign Date value to one of the properties from a dropdown Calendar list. But, user can also edit that field without using that dropdown calendar list by entering valid date value using Key board. These fields should not be editable manually.

Can anyone suggest me in doing this, such a way that the user can only choose date from drop down calendar and by default the field should be blank? Thanks in advance.