Success! Looks like we've fixed this one. According to our records the fix was applied for
a recent build.
Sencha Premium Member
Class System documentation change for apply and update methods.
Just a note on the documentation on the class system.
Your documentation here http://docs.sencha.com/touch/2-0/#!/guide/class_system says that there is an applyXXX method for the XXX config items. But it appears that there are actually 2 methods that should be taken into account applyXXX for transforming incoming values and updateXXX to perform side effects. http://mobile.dzone.com/articles/class-system-sencha-touch-2.
I've seen the update functions around occasionally and hadn't known really what they were for until I found this article. It would be good to clarify in the official documentation.
The update method has been around since the start so not sure how that was missed in the tutorial. Thank you for catching it and we will get that updated!