Feature Request: Better support for 'discnumber' field

I can access the 'discnumber' field by adding a dedicated column, but it's not showing on the left pane, so I don't know how to operate a multi selection and write disc number on several discs at once.
Could a field be added for disc number?

You may go to Mp3tag menu 'Extras/Options/Tag-Panel' and add the field of your choice.