edik

If FacadeX is active, the public WordPress sites are sent with the xhtml mime type. The internal sites like the administration panel and the login screen, which have many xhtml syntax errors, are still sent with the standard mime type.
You must ensure that your public sites have valid XHTML, otherwise you will get parsing errors in your browser.

FacadeX

Sends public sites with the XHTML mime type. The internal sites, which have many XHTML errors, are still sent with the HTML mime type.

mondalaci

Have you ever tried to validate a WordPress page that is full of Flash content and experienced some major pain throughout the process? If so, then this plugin is just for you!
Ultimate Flash XMTMLizer turns Flash embed code into well-formed XHTML by escaping object tags on the server side and unescaping them on the client side using JavaScript.

Ultimate Flash XHTMLizer

Turns Flash embed code into well-formed XHTML by escaping object tags on the server side and unescaping them on the client side using JavaScript.

FacadeX vs Ultimate Flash XHTMLizer