When working with nested lists content may be accidentally deleted

[Wiktor Walc]

In a certain situation, list items disappear.

Steps to reproduce

• Click bullet icon in editor
• Type 'test1' , press enter
• Indent the bullet
• Type 'test11' , press enter
• Type 'test12' , press enter
• Type 'test13'
• Move cursor behind test12
• Press enter 3 times
• Press backspace 4 times ( deleting the bullets ) . Note that test13 ends up one level lower
• Place cursor after 'test11'
• Press enter 3 times

After doing this, you will notice that all the subbullets (test11 and test12 ) are gone.

Tested on IE6, using ​http://ckeditor.com/demo

Also tested in IE8, the behaviour is a little different, but the result is the same (list items are gone).

It looks like this issue was introduced with [5380] (#4476).

[Paweł Horzela]

I'm sorry for attaching two patches - they are the same, I've just clicked 'Atach file' button two times by mistake.

This issue is connected with issue 6236 so remember to merge #6159.patch with #6236.patch.

[Paweł Horzela]

Patch

[Garry Yao]

A much reduced procedural:

1. Load the following content and selection;

   <ol>
       <li>
           test1
           <ol>
               <li>
                   test11^</li>
           </ol>
       </li>
   </ol>
   
   

1. Press one 'Enter' and 3 'Backspace' which should remain the list structure;
2. Now press 3 'Enter' and notice the result of the last one;
   • Actual Result: Last enter removes also list item 'test11'.

[Garry Yao]

The bug is not related to [5380] but the 'Backspace' key that handled by IE (not us) that transform the good list into a malformed one:

<ol>
    <li>
        test1
    </li>
    <ol>
         <li>
             test11^</li>
    </ol>
</ol>

We should show some tolerance to it when transforming.

[Garry Yao]

DUP of #6236.