Set Values of property control based on another property control

I have the below data table

Vendor Item Quantity
Vendor 1 Apple 4
Vendor 1 Orange 5
Vendor 2 Mango 8
Vendor 2 Grapes 9

I want the user to provide two dropdown lists using dropdown style property controls ( not filters). First dropdown  lists all vendors.Second dropdown should list only those items based on what user selects in first dropdown. So if user selects Vendor 1, then he/she should only see Apple and Orange in the second dropdown. Can anyone guide me how I can achieve this ?

(1) Answer