title: Netbeanw does not refresh JPanel after adding new components
body: <p>this title may not best describe my problem. I'm using Netbean GUI builder to create a JFrame and several JPanels. I create each JPanel in a seperate class, then I drag the JPanel class to JFrame. The problem is after dragging the JPanel to JFrame, if I add components to JPanel, it does not show the additional components in the JPanel contained in JFrame. I tried "clean and build" but the new component still not showing in JFrame -> JPanel.</p>