java.lang.NullPointerException
        at org.netbeans.modules.form.layoutdesign.LayoutUtils$ComponentIterator.findNext(LayoutUtils.java:546)
        at org.netbeans.modules.form.layoutdesign.LayoutUtils$ComponentIterator.next(LayoutUtils.java:563)
        at org.netbeans.modules.form.layoutdesign.LayoutUtils.contentOverlap(LayoutUtils.java:434)
        at org.netbeans.modules.form.layoutdesign.LayoutOperations.prepareGroupExtension(LayoutOperations.java:627)
        at org.netbeans.modules.form.layoutdesign.LayoutOperations.findIntervalToExtend(LayoutOperations.java:601)
        at org.netbeans.modules.form.layoutdesign.LayoutOperations.moveInsideSequential(LayoutOperations.java:472)
        at org.netbeans.modules.form.layoutdesign.LayoutFeeder.addInterval(LayoutFeeder.java:800)
        at org.netbeans.modules.form.layoutdesign.LayoutFeeder.add(LayoutFeeder.java:311)
        at org.netbeans.modules.form.layoutdesign.LayoutDesigner.addComponents(LayoutDesigner.java:826)
        at org.netbeans.modules.form.layoutdesign.LayoutDesigner.endMoving(LayoutDesigner.java:751)
        at org.netbeans.modules.form.HandleLayer$ResizeComponentDrag.end(HandleLayer.java:2823)
        at org.netbeans.modules.form.HandleLayer$ComponentDrag.end(HandleLayer.java:2464)
        at org.netbeans.modules.form.HandleLayer.endDragging(HandleLayer.java:1257)
        at org.netbeans.modules.form.HandleLayer.mouseReleased(HandleLayer.java:1813)
        at java.awt.Component.processMouseEvent(Component.java:6041)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3265)
        at java.awt.Component.processEvent(Component.java:5806)
        at java.awt.Container.processEvent(Container.java:2058)
        at java.awt.Component.dispatchEventImpl(Component.java:4413)
        at java.awt.Container.dispatchEventImpl(Container.java:2116)
        at java.awt.Component.dispatchEvent(Component.java:4243)
        at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4322)
        at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:3986)
        at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:3916)
        at java.awt.Container.dispatchEventImpl(Container.java:2102)
        at java.awt.Window.dispatchEventImpl(Window.java:2440)
        at java.awt.Component.dispatchEvent(Component.java:4243)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)