How to resize and move Backdrop in VSE?

Watching a VSE demo using the Gooseberry branch, the Backdrop can be resized and moved using V. Is there a way to resize and move the Backdrop in the 2.73 build?

The move feature may not be in the 2.73 release. Goosebery is a much more recent development version of blender.

I hope that this feature will make it in the regular release, as it is very useful, especially in full screen mode.