Cannot change font size in Xcode 4? Everywhere I look I see that in order to change the Font size in Xcode I simply click on the "fonts window button".
However, I can't.
I have a default install of Xcode, just started trying to use it the other day.  The fonts window button looks like this:
  

Notice how it is grayed out?  Nothing I can figure out will let me click on it to change the font size.  Is this a common problem?  Anyone have a clue how to fix it?
You have to select one or more categories in the list (on the right). Steps in Apple Docs