How PHPstorm handle encoding special HTML characters ?

What is the relationship between the meta tag in HTML files and encoding of the files and PHPSTorm ide (inspections, language injection, code formatting...)?

You can't change file encoding in PHPstorm if there is a meta charset defined. Bug or Feature ?

What if you change meta charset ? How can you then encode / format subsequently all the file Url / Special chars ?

At this point I m completely confused... Try to look in help... found nothing clear. Same in dev com... And this post added to my confusion : http://devnet.jetbrains.net/thread/290990

Richard