Exception in thread "Thread-0" org.eclipse.swt.SWTException: Failed to execute r
unnable (java.lang.IllegalArgumentException: Argument not valid)
        at org.eclipse.swt.SWT.error(SWT.java:3374)
        at org.eclipse.swt.SWT.error(SWT.java:3297)
        at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.ja
va:126)
        at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:3325)
        at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:2971)
        at impsoft.gui.GuiThread.run(GuiThread.java:318)
Caused by: java.lang.IllegalArgumentException: Argument not valid
        at org.eclipse.swt.SWT.error(SWT.java:3358)
        at org.eclipse.swt.SWT.error(SWT.java:3297)
        at org.eclipse.swt.SWT.error(SWT.java:3268)
        at org.eclipse.swt.widgets.Widget.error(Widget.java:435)
        at org.eclipse.swt.widgets.Widget.checkParent(Widget.java:268)
        at org.eclipse.swt.widgets.Widget.<init>(Widget.java:141)
        at org.eclipse.swt.widgets.Control.<init>(Control.java:96)
        at org.eclipse.swt.widgets.Scrollable.<init>(Scrollable.java:72)
        at org.eclipse.swt.widgets.Composite.<init>(Composite.java:93)
        at impsoft.gui.developer.appletShell.addHandler(appletShell.java:115)
        at impsoft.gui.tabs.runescapeTab$1.run(runescapeTab.java:54)
        at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35)
        at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.ja
va:123)
        ... 3 more