java.lang.AssertionError: Scene.validate was not called after last change. Widget is not validated. See first Q/A at http://graph.netbeans.org/faq.html page.
        at org.netbeans.api.visual.widget.Widget.paint(Widget.java:1459)
        at org.netbeans.api.visual.widget.Widget.paintChildren(Widget.java:1535)
        at org.netbeans.api.visual.widget.Widget.paint(Widget.java:1483)
        at org.netbeans.api.visual.widget.Widget.paintChildren(Widget.java:1535)
        at org.netbeans.api.visual.widget.Widget.paint(Widget.java:1483)
        at org.netbeans.api.visual.widget.SceneComponent.paint(SceneComponent.java:129)
        at javax.swing.JComponent.paintChildren(JComponent.java:842)
        at javax.swing.JComponent.paint(JComponent.java:1014)
        at javax.swing.JLayeredPane.paint(JLayeredPane.java:559)
        at javax.swing.JComponent.paintChildren(JComponent.java:842)
        at javax.swing.JComponent.paint(JComponent.java:1014)
        at javax.swing.JViewport.paint(JViewport.java:728)
        at javax.swing.JComponent.paintChildren(JComponent.java:842)
        at javax.swing.JComponent.paint(JComponent.java:1014)
        at javax.swing.JComponent.paintChildren(JComponent.java:842)
        at javax.swing.JComponent.paint(JComponent.java:1014)
        at javax.swing.JComponent.paintChildren(JComponent.java:842)
        at javax.swing.JComponent.paint(JComponent.java:1014)
        at javax.swing.JComponent.paintChildren(JComponent.java:842)
        at javax.swing.JComponent.paint(JComponent.java:1014)
        at javax.swing.JComponent.paintChildren(JComponent.java:842)
        at javax.swing.JComponent.paint(JComponent.java:1014)
        at org.netbeans.swing.tabcontrol.TabbedContainer.paint(TabbedContainer.java:968)
        at javax.swing.JComponent.paintChildren(JComponent.java:842)
        at javax.swing.JComponent.paint(JComponent.java:1014)
        at javax.swing.JComponent.paintChildren(JComponent.java:842)
        at javax.swing.JComponent.paint(JComponent.java:1014)
        at javax.swing.JComponent.paintChildren(JComponent.java:842)
        at javax.swing.JComponent.paint(JComponent.java:1014)
        at org.netbeans.core.windows.view.ui.MultiSplitPane.paint(MultiSplitPane.java:323)
        at javax.swing.JComponent.paintChildren(JComponent.java:842)
        at javax.swing.JComponent.paint(JComponent.java:1014)
        at org.netbeans.core.windows.view.ui.MultiSplitPane.paint(MultiSplitPane.java:323)
        at javax.swing.JComponent.paintChildren(JComponent.java:842)
        at javax.swing.JComponent.paint(JComponent.java:1014)
        at org.netbeans.core.windows.view.ui.MultiSplitPane.paint(MultiSplitPane.java:323)
        at javax.swing.JComponent.paintChildren(JComponent.java:842)
        at javax.swing.JComponent.paint(JComponent.java:1014)
        at javax.swing.JComponent.paintChildren(JComponent.java:842)
        at javax.swing.JComponent.paint(JComponent.java:1014)
        at javax.swing.JLayeredPane.paint(JLayeredPane.java:559)
        at javax.swing.JComponent.paintChildren(JComponent.java:842)
        at javax.swing.JComponent.paint(JComponent.java:1014)
        at javax.swing.JComponent.paintChildren(JComponent.java:842)
        at javax.swing.JComponent.paint(JComponent.java:1014)
        at javax.swing.JComponent.paintChildren(JComponent.java:842)
        at javax.swing.JComponent.paint(JComponent.java:1014)
        at javax.swing.JLayeredPane.paint(JLayeredPane.java:559)
        at javax.swing.JComponent.paintChildren(JComponent.java:842)
        at javax.swing.JComponent.paintWithOffscreenBuffer(JComponent.java:4970)
        at javax.swing.JComponent.paintDoubleBuffered(JComponent.java:4916)
        at javax.swing.JComponent.paint(JComponent.java:995)
        at java.awt.GraphicsCallback$PaintCallback.run(GraphicsCallback.java:21)
        at sun.awt.SunGraphicsCallback.runOneComponent(SunGraphicsCallback.java:60)
        at sun.awt.SunGraphicsCallback.runComponents(SunGraphicsCallback.java:97)
        at java.awt.Container.paint(Container.java:1709)
        at org.netbeans.core.windows.view.ui.MainWindow.paint(MainWindow.java:577)
        at sun.awt.RepaintArea.paintComponent(RepaintArea.java:248)
        at sun.awt.RepaintArea.paint(RepaintArea.java:224)
        at sun.awt.windows.WComponentPeer.handleEvent(WComponentPeer.java:254)
        at java.awt.Component.dispatchEventImpl(Component.java:4031)
        at java.awt.Container.dispatchEventImpl(Container.java:2024)
        at java.awt.Window.dispatchEventImpl(Window.java:1778)
        at java.awt.Component.dispatchEvent(Component.java:3803)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:463)
        at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:242)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)