I downloaded and installed Sencha cmd 5 and started working through the getting started guide. Note that I am a complete newbie with Ext-js.

I leave my command window open at the "Waiting for changes..." and I go out to lunch (Or just do different work). If I leave it like that for an hour or so I will get an error message stating


Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: sun.java2d.

HeadlessGraphicsEnvironment cannot be cast to sun.awt.Win32GraphicsEnvironment

at sun.awt.windows.WToolkit$3.run(WToolkit.java:758)

at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)

at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:733)

at java.awt.EventQueue.access$200(EventQueue.java:103)

at java.awt.EventQueue$3.run(EventQueue.java:694)

at java.awt.EventQueue$3.run(EventQueue.java:692)

at java.security.AccessController.doPrivileged(Native Method)

at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDo

main.java:76)

at java.awt.EventQueue.dispatchEvent(EventQueue.java:703)

at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThre

ad.java:242)

at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.

java:161)

at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThre

ad.java:150)

at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)


at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)


at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)

Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: sun.java2d.

HeadlessGraphicsEnvironment cannot be cast to sun.awt.Win32GraphicsEnvironment

at sun.awt.windows.WToolkit$3.run(WToolkit.java:758)

at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)

at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:733)

at java.awt.EventQueue.access$200(EventQueue.java:103)

at java.awt.EventQueue$3.run(EventQueue.java:694)

at java.awt.EventQueue$3.run(EventQueue.java:692)

at java.security.AccessController.doPrivileged(Native Method)

at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDo

main.java:76)

at java.awt.EventQueue.dispatchEvent(EventQueue.java:703)

at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThre

ad.java:242)

at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.

java:161)

at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThre

ad.java:150)

at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)


at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)


at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)


I am using Windows 7 64-bit on a Dell Laptop with an Intel Core I7 Quad core processor and 8GB of RAM if that helps.