Load iframe with editor in hidden DIV

[Damian]

When you try to load iframe with editor in hidden DIV and after that you change visibility of this div, the editor toolbar show without images of buttons (only alt of images are visible in buttons).
I reproduce this bug only in Firefox (for me it's FF 17.0.1 - Windows 7).
I've add test case for this issue in attachment.

[Michał]

The problem is not that buttons are 'missing' but that editor is set to high contrast mode. This is caused by both sides of comparison:

CKEDITOR.env.hc = hcDetect.getComputedStyle( 'border-top-color' ) == hcDetect.getComputedStyle( 'border-right-color' );

(in core/_bootsrap.js) are empty strings. This happens only in Firefox. In other browsers getComputedStyle returns red & blue.

[Jakub Ś]

I was able to reproduce this problem in Firefox only.

This particular TC can be reproduced from CKEditor 4.0.

I think the problem first started in CKEditor 3.5.2 rev [6454]. JS error is thrown with this revision:
URI: ckeditor/_source/core/dom/element.js
Message : TypeError: this.getWindow(...).$.getComputedStyle(...) is null
Line: 495

In CKEditor 3.6.5 something got changed that causes error in firebug script (at least in my browser). This continued to CKEDitor 4 beta and changed in CKEditor 4.0.

[Jakub Ś]

Another TC. Just put _mytest.html in samples folder and in Firefox you will see that editor goes into HC mode.

[Piotrek Koszuliński]

DUP of #11121.