title: Kettle spoon run in windows 10, always fails
body: <p>When I add a hop between two steps, it always goes wrong.</p>
  
  <pre><code>一个未预期的错误发生在Spoon: probable cause:在停止Spoon前，请先关闭其它spoon窗口! 
  </code></pre>
  
  <p>null</p>
  
  <pre><code>java.lang.NullPointerException
      at org.pentaho.di.ui.spoon.trans.TransGraph.addHop(TransGraph.java:1537)
      at org.pentaho.di.ui.spoon.trans.TransGraph$8.widgetSelected(TransGraph.java:1496)
      at org.eclipse.swt.widgets.TypedListener.handleEvent(Unknown Source)
      at org.eclipse.swt.widgets.EventTable.sendEvent(Unknown Source)
      at org.eclipse.swt.widgets.Widget.sendEvent(Unknown Source)
      at org.eclipse.swt.widgets.Display.runDeferredEvents(Unknown Source)
      at org.eclipse.swt.widgets.Display.readAndDispatch(Unknown Source)
      at org.pentaho.di.ui.spoon.Spoon.readAndDispatch(Spoon.java:1316)
      at org.pentaho.di.ui.spoon.Spoon.waitForDispose(Spoon.java:7979)
      at org.pentaho.di.ui.spoon.Spoon.start(Spoon.java:9310)
      at org.pentaho.di.ui.spoon.Spoon.main(Spoon.java:654)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.lang.reflect.Method.invoke(Method.java:606)
      at org.pentaho.commons.launcher.Launcher.main(Launcher.java:92)
  </code></pre>