CwCrop was update to version 0.8, thanks a lot to Harm Hermsen!
As Harm Hermsen pointed out, there were two bugs: One was the possibility of selecting an area smaller than minsize, another one was a 1pixel error when trying to select the whole image. He also delivered the bugfix, very cool!
If you update CwCrop to 0.8 – you also need to make this change in the HTML structure: The imglayer-DIV needs these additional CSS properties:
padding: 1px; background-position: center center;