Uh..have you never heard of IntelliJ IDEA or Eclipse? Or RubyMine? Or Netbeans even...
They pretty much do everything you're talking about.
They pretty much do everything you're talking about.
IntelliJ IDEA has exactly what the author implemented, but IntelliJ IDEA can also take about 5 minutes to start up, and takes up all your screen real estate. When you work in 5 languages on a regular basis and just want your editor to start up quickly, that can be quite a pain.
The only navigation I can see for open projects is the tree view which is painful for large projects with files scattered across the project (e.g. web frameworks).
edit: Ah, I see. The article wasn't about text editors. It was about how file navigation (within whatever environment you use) sucks.
Both add better file/class/method navigation, and I find them invaluable.