Thread:Extension talk:WYSIWYG/IE8 Compatibility View mode breaks the editor/reply

IE Compatibility view(IE8 & IE9) means it will behave as IE7. You can change the Document Mode using DOCTYPE or meta tag but for intranet sites Browser Mode can only be changed by Developer Tools or IE settings. CKeditor is compatible with IE7 but WYSIWYG is not because mediawiki plugin of CKeditor is not written using jQuery. So, you need to use jQuery to make it work as jQuery is already available on the page.