Yeah their preferred convention is purposeControlType as in setBackgroundButton. Kind of silly considering how dead-set they are against using a control name prefix as in btnSetBackground.
Some developers argue that you should leave off the control entirely because it shouldn't matter what kind of control it is. For example, it shouldn't matter whether setBackground is a button, menu item, or something else. But then what do you do if you want to have a menu and a button?
It doesn't really matter as long as you're consistent.
I'm glad you like the book. Post a review when you have a chance!