Strange jumps to the top in Firefox upon dialog closing (testcase included)

[Сковорода Никита Андреевич]

Affects Firefox 20.0 (the latest version atm). Does not affect WebKit-based browsers.

Reproducable: Always.

Steps to reproduce:

1. Open full-featured CKEditor, for example, ​http://ckeditor.com/demo#full
2. Switch to source mode.
3. Paste this code:

   <p>Foo.</p>
   <p>Foo.</p>
   <p>Foo.</p>
   <p>Foo.</p>
   <p>Foo.</p>
   <p>Foo.</p>
   <p>Foo.</p>
   <p>Foo.</p>
   <p>Foo.</p>
   <p>Foo.</p>
   <p>Foo.</p>
   <p>Foo.</p>
   <p>Foo.</p>
   <p>Foo.</p>
   <p>Foo.</p>
   <p>Foo.</p>
   <p>Foo.</p>
   <p>Foo.</p>
   <div style="float:right">
   <p><img alt="" src="http://b.cksource.com/a/1/img/sample.jpg" style="height: 200px;" /></p>
   <p><img alt="" src="http://b.cksource.com/a/1/img/sample.jpg" style="height: 200px;" /></p>
   <p><img alt="" src="http://b.cksource.com/a/1/img/sample.jpg" style="height: 200px;" /></p>
   <p><img alt="" src="http://b.cksource.com/a/1/img/sample.jpg" style="height: 200px;" /></p>
   </div>
   

4. Switch to WYSiWYG mode.
5. Scroll to the bottom, make sure you don't see any of the «Foo» labels in the viewport.
6. Double-click on the last image. A dialog will appear.
7. Press «OK» to apply and close the dialog.

What actually happens: The CKEditor viewport is instantly scrolled to top (jumps).

What should happen: The viewport should remain as it is. If the height is changed after editing the image, the top border of the visible area should remain the same, and the viewport should extend to the bottom (as it does when everything is fine).

Additional notes: Clicking the last image is not requred, you can use either one. This depends on if the text at the left (the «Foo» lines) is in the viewport. If you can still see the text (not scrolled down or the viewport is large enough), then the bug won't trigger.

[Сковорода Никита Андреевич]

Also reproducable in latest (atm) CKEditor nightly build: ​http://nightly.ckeditor.com/13-04-07-14-51/full/samples/replacebyclass.html

[Сковорода Никита Андреевич]

Noticed another thing.

When the «Foo» label is in the CKEditor viewport, but the CKEditor itself isn't fully visible (scrolled up a bit, so no «Foo» labels are in the actual browser viewport), CKEditor viewport does not get scrolled to the top, but the browser viewport does instead.

[Сковорода Никита Андреевич]

A video demonstration of both jumps.

[Jakub Ś]

Problem can now be reproduced in both branches CKE 3.x and CKE 4.x (v4) from CKEditor 3.4.1.

This issue is very similar to #7973. This ticket may be in fact duplicate of #7973 however TC reported here isn't reproducible in IE and in Firefox it has been reproducible from CKEditor 3.3.1 (not 3.3 as mentioned in #7973).