This is an email address!!! Just substitute the "(at)" for an "@" ...
Perfection as a goal is a nice idea that can point one in a specific direction. However, since "perfection" is an ever changing (evolving?) and moving target, one must admit that perfection can never be obtained...
I can't say the reason for the stack overflow and looks to be a framework issue. I can say that absolutely positioning your form elements is going to make your life very hard. Suggest reading the Getting started guide(s) (bottom right) http://www.sencha.com/products/designer/
Sencha Architect Development Team