Calling setContentPane() on JRibbonFrame with a JPanel results in the ribbon
failing at runtime with an error about the "ribbon not being visible."
Regardless, for consistency with the rest of the API (such as setJMenuBar,
setLayout, etc.), it would be better to just prevent this method from being called.
I found this while adapting an existing application to use the JRibbonFrame
parent class instead of JFrame; others may see the same bug when adapting an
This is a low priority issue, now that I've figured out what I was doing wrong.