Check out example codes for "how to change top of window in java". It will help you in understanding the concepts better.

Code Example 1

UIDefaults uiDefaults = UIManager.getDefaults();
uiDefaults.put("activeCaption", new javax.swing.plaf.ColorUIResource(Color.gray));
uiDefaults.put("activeCaptionText", new javax.swing.plaf.ColorUIResource(Color.white));
JFrame.setDefaultLookAndFeelDecorated(true);

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