Steps to reproduce:

1. Configure new image variation with huge dimensions, for instance (ezplatform.yml):

   ezpublish:
       system:
           admin_group:
               image_variations:
                   big:
                       reference: null
                       filters:
                           - { name: geometry/scaledownonly, params: [2000, 1600] }
   

2. Create the new article. In RichText field embed an image (use Image from Richtext menu, not embed).
3. Select the variation created in the step 1.

Result:
The image doesn't fit in the editor's window.

Expected result:
The image should be automatically scaled to fix in editor's window.

Please see the attached screenshot.