If you want to read about GUI changes,
Java 7 New Features Cookbook has two chapters on them. Normally, I wouldn't plug a similar book during a promo, but this book is nothing like the Well Grounded Java Developer. They target completely different things.
Chapter 7: Graphical User Interface Improvements
Introduction
Mixing heavyweight and lightweight components
Managing window types
Managing the opacity of a window
Creating a varying gradient translucent window
Managing the shape of a window
Using the new border types in Java 7
Handling multiple file selection in the FileDialog class
Controlling the print dialog box type
Using the new JLayer decorator for a password field
Up
Chapter 8: Handling Events
Introduction
Managing extra mouse buttons and high resolution mouse wheels
Controlling a focus when displaying a window
Using secondary loops to mimic modal dialog boxes
Handling spurious thread wakeups
Handling applet initialization status with event handlers