Auto Commit Changes with the Transform tool in Photoshop CC doesn't allow you to bring in a new guide without committing the change.
In the middle of Transforming an image, I often need to bring in a new guide to see if I've transformed it enough or too much. This is particularly true when using the Skew, Distort, or Warp options. As soon as I go to drag in a new guide, the Transform is accepted. I then need to do a new transform to correct the change. Please change this to allow you to hold down the Command, Shift, Option, whatever key during Transform so that you can bring in new guides with committing the change.