**System Information**
Windows 7
Intel Core i7
AMD r7 200
**Blender Version**
Broken: 2.76b
Worked: 2.75a
**Short description of error**
Unwrap from marked seams is not update seams information.
**Exact steps for others to reproduce the error**
I try to make an unwrap with "U" key after mark the seams, but the unwrap is not work. Simply no update the seams information.