Buttons in Sencha Arch

I'm having a hard time getting button icons to work in Sencha Architect. Is there some special vudo for getting these to work? Also, how do I get a list of available button icons?



Also, I'm SO glad I bought this product, it's totally awesome and has saved me tons of time. I'm DevOps building tools to make AWS CloudFormation easier for Intuit. Good stuff ;)