Bug 166015 Refactor designer actions to eclipse command framework
Eclipse command framework provide a more explicit way to manage UI actions contributions, we can take it's advantage to make our actions code more clean and maintainable.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/editors/schematic/actions/InsertGroupActionFactory.java
}
	protected ListBandProxy getListBandProxy( )
	{
		if ( currentModel instanceof ListBandProxy )
		{
			return (ListBandProxy) currentModel;
		}
		return null;
	}
	/**
	 * Gets the activity stack of the report
	 * 
	 * @return returns the stack
	 */
	protected CommandStack getActiveCommandStack( )
	{
		return SessionHandleAdapter.getInstance( ).getCommandStack( );
	}
	/**
	 * Returns the current position of the selected part
	 * 
	 * @return the current position of the selected part
	 */
	protected int getCurrentPosition( )
	{
		if ( currentModel != null && isGroup( ) )
		{
			if ( getRowHandle( ) != null )
			{
				DesignElementHandle group = getRowHandle( ).getContainer( );