Debugging Sencha Touch in Google Chrome: How to set a breakpoint?

while trying to debug the NestedList title bug

http://www.sencha.com/forum/showthread.php?161303-NestedList-example-from-Github-updateTitleText-not-working

I was able to set a breakpoint using Google Chrome -> Tools -> Developer Tools, in my own javascript, but I am not able to set any breakpoint in the sencha-touch-debug.js script.

Is there a way to set a breakpoint in sencha-touch-debug.js ? Or is there any better way to debug the Sencha touch core?