Thanks for the info, I'm going to look into it out a little bit later.
In this case ($this = this), it seems a little bit of jquery philosophy snuck-in. Since jQuery is no-where close to ExtJs as far as scoping is concerned, so I tend to emulate scoping by defining '$this' as the current 'this', so when i'm in a different scope, I can recall $this later. Some people do "var self = this;" but I like the '$' prefix, what can i say! :-)