[FF] HC mode enabled when editor loaded in hidden iframe

[RichardD]

As reported in the forums: ​http://ckeditor.com/forums/CKEditor/Problem-with-icons-showing-up-in-Firefox-using-thickbox

Displaying a CKeditor instance inside an iframe which is initially set to "display:none" incorrectly triggers the HC detection, and none of the toolbar icons show up.

This seems to be related to Firefox bug 548397 - "window.getComputedStyle() returns null inside an iframe with display: none". ​https://bugzilla.mozilla.org/show_bug.cgi?id=548397

Looking at _bootstrap.js, line 24, the problem is obvious:

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

Since getComputedStyle is returning null, this test is setting env.hc to true.

[Jakub Ś]

I was able to reproduce this particular scenario from CKEditor 4.0.
In CKEditor 4.0 beta error was thrown: this.getWindow(...).$.getComputedStyle(...) is null

It works fine in CKEditor 3.x.

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To reproduce just put test.html in samples folder and open it in a browser

[Jakub Ś]

To workaround you can use position:relative and left:-3000px;

[Piotrek Koszuliński]

Pushed ​t/11121 on dev and tests.

[Piotrek Koszuliński]

Closed older duplicate in #9802.

[Marek Lewandowski]

I've pushed minor change to tests code.

One thing still remains - now we have issue in reversed situation:
in FF having High Contrast on, when we will follow this ticket TC, we will end up with CKEDITOR.env.hc evaluated to false. (It works fine with IE10 though)

Can we still fix that? Maybe with diffrent approach, focusing on bg images rather than borders, like in ​SO topic?

[Piotrek Koszuliński]

So what's the value returned by getComputedStyle if high contrast is on? I mean the normal case - not a hidden iframe case, which we can ignore.

[Marek Lewandowski]

in normal case it's correct, the only one invalid situation is when editor is not displayed - even if HC is on it will tell that HC is off

[Piotrek Koszuliński]

Then I think that it is a situation which we can accept. When iframe is hidden getComputedStyle will always return useless values, so most of short ways for HC discovery will fail. The goal was to fix the far more important case when env.hc is set to true even though HC is not enabled.

[Marek Lewandowski]

Then solution is ok, and closes this issue.

[Piotrek Koszuliński]

Fixed on master with ​git:ac648cc on dev and 81b848a on tests.