How to shrink volume on an SSD? [duplicate]

How do I shrink an SSD partition? When I try to shrink the volume, the "available amount of space to shrink" is zero. I did a disk defragmentation (I know it's bad), but it still comes up with zero. Any tips or pointers?

I am using Windows 7, Vertex 2 240 GB, MacBook Pro, NTFS, and I have about 70 GB used. I also turned off hibernation and turned off paging to reduce large files.

Often this is caused by an unmovable file at the end of the partition.

"Shrink volume" actually calls into the disk defragmenter API to move blocks around. If it is unable to move a block, then it'll still be unable to move the block if you manually launch the Windows disk defragmenter.

The answer to this question describes how to check for unmovable files: How to shrink Windows 7 boot partition with unmovable files

A great tool for managing partitions is GParted, works great. It works on both Windows and Linux.