Thank you for writing.
I would need your initial setup to be able to answer your question adequately. But as a general to get the value of the property when it is changed, you can subscribe to RadPropertyGrid PropertyValueChanged event. This event is fired every time a value of a property is changed. You can access the items in RadPropertyGrid by using the Items collection where you can use either property name or index.
If this does not help you, I would kindly ask you to provide a more detailed explanation of your setup and your scenario. How do you populate the RadPropertyGrid, do you use RadPropertyStore and how you want the whole process to work out.
I am looking forward to your reply.
the Telerik team