TinyMCE is the WYSIWYG editor used in the platform in versions 6.0 to 8.2. It is a third-party product by Moxiecode Systems. It is a web based Javascript HTML WYSIWYG editor control released as Open Source under LGPL.
There are no plans to upgrade the integration in older releases as the customization required to work within the platform is not supported. In addition, we have changed to a new WYSIWYG editor called CKEditor in the most recent releases of the platform.