Bug 124600 delete Grid Column causes NPE thrown out in error log
steps to reproduce: - insert a 3*3 grid - delete grid columns one by one expected behavior: - these operations should completed without any error. actual behavior: - after i deleted the 3rd column, NPE was thrown out in error log.
UI/org.eclipse.birt.report.designer.core/src/org/eclipse/birt/report/designer/util/DNDUtil.java
if ( selection instanceof StructuredSelection )
		{
			return handleValidateDragInOutline( ( (StructuredSelection) selection )
					.toArray( ) );
		}
		if ( selection instanceof Object[] )
		{
			Object[] array = (Object[]) selection;
			if ( array.length == 0 )
			{
				return false;
			}
			if ( array[0] instanceof ColumnHandle )
			{
				boolean bool = false;
				int columnNumber = HandleAdapterFactory.getInstance( )
						.getColumnHandleAdapter( array[0] ).getColumnNumber( );
				Object parent = ( (ColumnHandle) array[0] ).getContainer( );
				if ( parent instanceof TableHandle )
				{
					bool = ( (TableHandle) parent )
							.canCopyColumn( columnNumber );
				}
				else if ( parent instanceof GridHandle )
				{
					bool = ( (GridHandle) parent ).canCopyColumn( columnNumber );
				}
				if ( bool && array.length == 1 )
				{
					return true;