面板（panel）是ExtJS中一个很重要的概念，它相当于一幅画板，我们可以在它上面放置需要的各种组件，并使用不同的布局类对组件的摆放位置进行格式化，掌握这些布局类的特点及使用方式是突破ExtJS页面设计的关键。-Panel (panel) is ExtJS is a very important concept, it is equivalent to a drawing board, we can put on it needs a variety of components, and use a different layout of the component placement class format, master these features and layout classes used ExtJS page design is the key to a breakthrough。