Bug 146371 [Regression]Error happens when switching to script view
Steps to reproduce: 1.New a report 2.Choose Page->Script Expected result: Switch to script view Actual result: org.eclipse.jface.util.Assert$AssertionFailedException: null argument; at org.eclipse.jface.util.Assert.isNotNull(Assert.java:150) at org.eclipse.jface.util.Assert.isNotNull(Assert.java:126) at org.eclipse.birt.report.designer.internal.ui.dialogs.ExpressionTreeSupport.addDropSupportToViewer(ExpressionTreeSupport.java:653) at org.eclipse.birt.report.designer.internal.ui.editors.script.TreeViewPalettePage.createControl(TreeViewPalettePage.java:84) at org.eclipse.birt.report.designer.internal.ui.editors.schematic.ReportMultiBookPage.setActivePage(ReportMultiBookPage.java:198) at org.eclipse.birt.report.designer.ui.editors.MultiPageReportEditor.updatePaletteView(MultiPageReportEditor.java:497) at org.eclipse.birt.report.designer.ui.editors.MultiPageReportEditor.updateRelatedViews(MultiPageReportEditor.java:585) at org.eclipse.birt.report.designer.ui.editors.MultiPageReportEditor.pageChange(MultiPageReportEditor.java:524) at org.eclipse.ui.forms.editor.FormEditor.setActivePage(FormEditor.java:596) at org.eclipse.ui.forms.editor.FormEditor.setActivePage(FormEditor.java:502) at org.eclipse.birt.report.designer.ui.editors.actions.PageSetAction.run(PageSetAction.java:50) at org.eclipse.jface.action.Action.runWithEvent(Action.java:499) at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:539) at org.eclipse.jface.action.ActionContributionItem.access$2(ActionContributionItem.java:488) at org.eclipse.jface.action.ActionContributionItem$5.handleEvent(ActionContributionItem.java:400) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:66) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:928) at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3348) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:2968) at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:1914) at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:1878) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:419) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149) at org.eclipse.ui.internal.ide.IDEApplication.run(IDEApplication.java:95) at org.eclipse.core.internal.runtime.PlatformActivator$1.run(PlatformActivator.java:78) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:92) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:68) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:400) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:177) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:324) at org.eclipse.core.launcher.Main.invokeFramework(Main.java:336) at org.eclipse.core.launcher.Main.basicRun(Main.java:280) at org.eclipse.core.launcher.Main.run(Main.java:977) at org.eclipse.core.launcher.Main.main(Main.java:952)
UI/org.eclipse.birt.report.designer.ui.editors.schematic/src/org/eclipse/birt/report/designer/internal/ui/editors/script/TreeViewPalettePage.java
tree.dispose( );
		treeCommon.dispose( );
	}
	/**
	 * @see IAdaptable#getAdapter(java.lang.Class)
	 */
	public Object getAdapter( Class adapter )
	{
		return null;
	}
	/**
	 * @return the palette viewer's control
	 * @see Page#getControl()
	 */
	public Control getControl( )
	{
		return tree;
	}
	/**
	 * Sets focus on the palette's control
	 * 
	 * @see Page#setFocus()
	 */
	public void setFocus( )
	{
		tree.setFocus( );
	}
	public ExpressionTreeSupport getSupport( )
	{
		return this.treeCommon;