This is a custom panel subclass to achieve a different look and feel while not changing the default appearance of an Ext.Panel.

The js is not minified so it is readable. See BubblePanel.js and bubble-panel.js.

The majority of the work is actually done in bubble.css. Ext.ux.BubblePanel defines a custom baseCls ('x-bubble') which will generate unique CSS classes for the markup in a Panel such as 'x-bubble-tl', 'x-bubble-tr' and 'x-bubble-tc'.