The image editor seems to be disabled in some scenarios but I can't figure out how to enable it. I am even able to reproduce on one of the demos. Here are the steps to reproduce:

1. go to the main demo : http://richtexteditor.com/demo/
2.  highlight one of the images
3. either right-click or press the "img" tag in the breadcrumb at the bottom of the screen and you will see the disabled "image editor" menu item:

Tested in IE10, IE 11 and Chrome.