Saving changes is not permitted in MS SQL Management studio
When you modify columns of a table in MS SQL management studio, you got the message "Saving changes is not permitted. The changes you have made require the following table to be dropped and re-created … " (Figure 1). The reason of this is re-creating of table. It's really important for productive environment but not very for test ones.
To fix this you should change one setting in MS SQL Management studio:
Go to "Tools / Options / Designers / Table and Database Designers" and turn off value "Prevent saving changes that require table re-creation" (Figure 2).