I'm not familiar with Renoise, but according to this tutorial it's possible to configure VSTs for a Windows environment.
So, if you're using Windows, here's your solution:
I personally use MAnalyzer.
If you don't like any of the solutions OR you're not using Windows you should try googling:
spectrum analyzer
I'm aware that you did ask for a 'static' graphical analyzer, but I'm wondering if you're problem is that the master spectrum is capturing the whole song instead of a single channel.
And btw: I really wouldn't recommend anyone to do audio changes based on a graphical spectrum - music is about what you hear, and not what you listen.
While doing that is fine when experimenting, it shouldn't become something you do all the time.