Bug 147687 Assert err happened with design ui
Run BIRT in workbench with argument -ea. Assert err happened when using design ui to open a design file.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/dialogs/ExpressionTreeSupport.java
}
	private TreeItem createSubTreeItem( TreeItem parent, String text,
			Image image, String textData, String toolTip, boolean isEnabled )
	{
		TreeItem item = new TreeItem( parent, SWT.NONE );
		item.setText( text );
		if ( image != null )
		{
			item.setImage( image );
		}
		item.setData( ITEM_DATA_KEY_TOOLTIP, toolTip );
		item.setData( ITEM_DATA_KEY_TEXT, textData );
		item.setData( ITEM_DATA_KEY_ENABLED, new Boolean( isEnabled ) );
		return item;
	}
	private TreeItem createSubFolderItem( TreeItem parent, String text )
	{
		return createSubTreeItem( parent, text, IMAGE_FOLDER, true );
	}
	private TreeItem createSubFolderItem( TreeItem parent, IClassInfo classInfo )
	{
		return createSubTreeItem( parent,
				classInfo.getDisplayName( ),
				IMAGE_FOLDER,
				null,
				classInfo.getToolTip( ),
				true );
	}
	private void createSubTreeItems( TreeItem parent, String[][] texts,
			Image image )