I need to make control by allowing end-user to specify some extra information for each class or operator, like I want to give each class/operator an extra attribute like: Component_Type , this Component_Type must have 3 values : 1,2,null , so I need a strong mechanism to allow user to choose only one value of those values instead of typing values, why? because if user by mistakes enters number like:0,4,-3, 5,.... which are not in my List of Component_Type, then my Add-in will not be able to recognize these strange numbers which entered by mistakes, so My Idea is to restrict the User to select from read only menu: which offers just only 3-read only values.
I would like user to specify what I need, this give more quality and more precision, my add-in can only classify each class or operator into 3 groups only, Group1 for value 0, and Group 2 for value 1, and Group 3 for null values, imagine if there is no read-only drop down list: then user can enter any wrong number which affect the whole process used by my add-in.
So again I am looking for a mechanism/way to prevent User from entering any arbitrary values.
Regards,