I have trouble with Wordpress. I wish to produce a text widget with title as

Support &lifier FAQ

Consider I wish to validate XHTML, I'm writing it as being Support & FAQ

The issue is after i save the widget in iBlogpro Theme, amplifier is transformed to simple &lifier by Wordpress.

Perhaps you have attempted using: &?

Edit even when Wordpress changes the & to &lifier within the title from the widget, it'll produce a & within the HTML. So, your XHTML validations shouldn't provide you with problems.