Right clicking on a readonly link causes a TypeError

[NielsNet]

Are you reporting a feature request or a bug?

Bug

Provide detailed reproduction steps (if any)

1. Open a page with a CKEditor (SDK Sample)
2. Make it readonly without focussing the editor first
3. Right-click on a link

Expected result

Nothing

Actual result

A typeerror is thrown in the browser-console:

ckeditor.js:664 Uncaught TypeError: Cannot read property 'checkReadOnly' of undefined
    at Array.<anonymous> (ckeditor.js:664)
    at $.onShow (ckeditor.js:723)
    at Object.onShow (ckeditor.js:29)
    at $.show (ckeditor.js:725)
    at $.open (ckeditor.js:735)
    at $.<anonymous> (ckeditor.js:734)
    at ckeditor.js:27

Other details

• Browser: Opera, Chrome, MS Edge
• OS: Windows 10
• CKEditor version: 4.7.3
• Installed CKEditor plugins: undefined

[msamsel]

I was able to reproduce it on Chrome 62 Win7.
Problem wasn't present on Edge and Chrome on MacOS.

[mlewand]

I can also repro it with vanilla CKEditor 4 on http://cdn.ckeditor.com/4.8.0/full/samples/old/readonly.html.

Looks like a regression introduced in 4.4.6.

Fails in http://cdn.ckeditor.com/4.4.6/full/samples/readonly.html

Works on http://cdn.ckeditor.com/4.4.5/full/samples/readonly.html

[jacekbogdanski]

With 4.4.6 version (3048943) we moved initial selection fix from the selection constructor to editable. With this change initial selection fix is executed on the editor focus event, probably removed or replaced by another focus event listener.

[mlewand]

Fix has been merged to next branch, and will be released in CKEditor 4.10.2.

You can already take a peek at it in our CKEditor preview builds. The simplest way would be to reuse our legacy read-only sample - be sure to press "Make it read-only" button, and then right click the link without focusing the editor.