Why would you use one instead of a JFrame? You can programmatically maximise a JInternalFrame with setMaximum( boolean ) or iconify/minise it with JInternalFrame. setIcon( boolean ). You can specify whether the JInternalFrame internal frame has the window decorations to support resizing, iconifying, closing, and maximizing.

You don’t directly embed your JInternalFrames as components in a JFrame. Unlike JPanels, JInternalFrames are free to be moved around anywhere inside the mother JFrame, not constrained by a layout manager. So you declare a DesktopPane object for your JFrame and then add your JInternalFrames to that.

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