Image Crop Feature

[Tom.]

Hello, 

I noticed that there was a way to crop images once uploaded using the image crop feature shown here: 

https://processwire.com/blog/posts/image-editing-features-continued-2.5.20/#more-image-editing-features

However I'm running 2.6.18 dev and it's not there. Click the title just brings the image up in a light box also no crop icon shows. 

How do I activate it? 

Thanks,

Tom

EDIT:

Sorry, I just realised that this was only available on images just uploaded with the page not yet saved, not with images already on a saved page. Not sure if this is intended functionality.