GWT provides a lot of leverage on building complex user interfaces, but web browsers always do their best to make it harder than it should be. Fortunately, widgets provide a natural way to "wrap up" complex functionality, making it easy to reuse and share. In this session, Joel Webber will explain the inner workings of the widget library, as well as common patterns and pitfalls. Topics will include creating new widgets and panels, memory management, event handling, and interacting with the browser DOM.