Modify tables and columns in design mode

By default, in SQL Server 2008, prevent from saving changes in Design mode.
If you modify some table in design mode, probably appears the message "Saving changes is not permitted"

Desing Mode


Warning Message

For changing this option, go to Tools menu, Options, Designers tree option, and Table and Database Designers option. (You can see in next picture).

I hope that this article is usefull for you.