Your question was already answered in the other thread you have opened - "PropertyGrid refresh problem". I am copying the answer here as well, so the community can benefit from it:
You can observe the same behavior with the standard property grid control. We strive to keep the behavior consistent with the standard controls, but this is something we can improve. I have logged this as a feature request in our Public Issue Tracking System - PITS. We will make sure this is included in our next major release. You can track the progress of the feature and add your vote/comment on the following link - PITS Feature.
We would like to kindly ask you to use just one support channel to contact us. Posting the same question more than once slows down our response because we will need to review and address two or more threads instead of one. Furthermore, please have in mind that support threads are handled according to the license type and time of posting, so if it is an urgent issue, we suggest that you use a support ticket, which would be handled before a forum thread.
the Telerik team