1) Run the RichTextEditor
2) As you can see there are already some images inserted in the document
3) Right click on any image , and click Edit Image, Image editor dialog box does open up. (as shown in the attached pic EditImageActive1.jpg)
4) click outside the image and right click on the image again, and this time you can see the Edit image option is disabled and this happens consistently. (as shown in the attached pic EditImageInactive.jpg)

One more thing to observe was upon right clicking the image sometimes the Edit image option does show up in the context menu and a different menu appears (as shown in the attached pic NoEditImageOption1)