Bug 175664 [Mac] Unexpected internal exception occurs when invoke expression builder
Description: There are two problems: 1. "fx" button (Click this button to invoke Expression Builder) could not be displayed correctly, nothing displayed in the button. 2. Click on the button, an unexpected internal exception occurs. Version:2.2.0.v20070205 Steps to reproduce: 1.Insert a Data item to the layout. Click "fx" button to invoke the expression builder, although on Mac "fx" button could not display correctly. Error log: Argument cannot be null Plug-in Provider: Eclipse.org Plug-in Name: BIRT Designer UI Plug-in ID: org.eclipse.birt.report.designer.ui Error Code: Error.GUIException.invokedByUnexpectedException Error Message:Argument cannot be null
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/util/UIUtil.java
}
		catch ( SemanticException e )
		{
			ExceptionHandler.handle( e );
			return false;
		}
	}
	private static boolean addGroup( DesignElementHandle parent, int position )
			throws SemanticException
	{
		GroupHandle groupHandle = null;
		SlotHandle slotHandle = null;
		
		DesignElementFactory factory = DesignElementFactory.getInstance( parent.getModuleHandle( ) );
		if ( parent instanceof TableHandle )
		{
			groupHandle = factory.newTableGroup( );
			slotHandle = ( (TableHandle) parent ).getGroups( );
			int columnCount = ( (TableHandle) parent ).getColumnCount( );
			groupHandle.getHeader( ).add( factory.newTableRow( columnCount ) );
			groupHandle.getFooter( ).add( factory.newTableRow( columnCount ) );
		}
		else if ( parent instanceof ListHandle )
		{
			groupHandle = factory.newListGroup( );
			slotHandle = ( (ListHandle) parent ).getGroups( );
		}
		if ( groupHandle != null && slotHandle != null )
		{
			slotHandle.add( groupHandle, position );