How to show/reveal hidden or invisible characters in NetBeans?

Question

How can you show/reveal hidden characters in NetBeans? In other editors, if this feature is turned on, a space might be shown as a small centered dot, and a tab as a right

Answer 1

Ubuntu 11.10 => Netbeans 7.0.1

The "View → Show Non-printable Characters" mode really not shows whitespaces while font was not installed by me.

Thanks!