Keyboard navigation problem with tabs in image dialog

[damo]

To Reproduce the Issue on the Link Tab.

Open the CK Editor.
Access the Tool bar by Pressing(ALT+F10)
Navigate to Insert Image Icon.
Press Enter.
on the Insert Image Light Box Navigate to Link Tab by Pressing Alt+F10 and then Press Tab
Press Enter.

Actual result: Focus is going no where..The User has to Press Tab twice in order for the Focus to go back in to the First Field.which is URL Text Field.so JAWS is not Reading any thing until the User Press the Tab Key Twice..This will confuse the User whether he is on the Light Box..or the Focus has gone out of the Window.

This will also happen when you Reach the Cancel Link and then we have to Press Tab Twice in order for the Focus to go back to URL Text Field..

Expected result: Focus should go to the URL Text Field and JAWS should Read URL Edit Type and Text..so the User can Understand that there is an Input Text box.

[garry.yao]

Similar with #4542.

[fredck]

The fix works well. The only issue is that we already have isVisible in CKEDITOR.dom.element. It should be verified and eventually amended, if needed.

[fredck]

Btw... there are test files in the patch that are not anymore available on trunk.

[fredck]

There are extra curly braces being added to the isVisible function. Surprisingly it works, but it must be fixed.

Other than that, we may fix the implementation to make it perform a bit better:

isVisible : function()
{
	var isVisible = !!this.$.offsetHeight && this.getComputedStyle( 'visibility' ) != 'hidden',
		elementWindow;

	// Webkit and Opera report non-zero offsetHeight despite that
	// element is inside an invisible iframe. (#4542)
	if ( isVisible && ( CKEDITOR.env.webkit || CKEDITOR.env.opera ) )
	{
		elementWindow = this.getWindow();
		
		if ( !elementWindow.equals( CKEDITOR.document.getWindow() )
			&& ( elementWindow = elementWindow.$.frameElement ) )
		{
			isVisible = new CKEDITOR.dom.element( elementWindow ).isVisible();
		}
	}

	return isVisible;
}

[garry.yao]

It seems that I really need to lint before patching these days ;)

[fredck]

Please fix coding style for the if block at line 752 before committing.

[garry.yao]

Fixed with [4534].