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 ( array.length == 1 )
			{
				return handleValidateTargetCanContain( targetObj, array[0],
						validateContainer );
			}
			int canContainAll = CONTAIN_NO;
			for ( int i = 0; i < array.length; i++ )
			{
				int canContain = handleValidateTargetCanContain( targetObj,
						array[i], validateContainer );
				if ( i == 0 )
				{
					canContainAll = canContain;
				}
				if ( canContain == CONTAIN_NO || canContain != canContainAll )
				{
					return CONTAIN_NO;
				}
			}
			return canContainAll;
		}
		else
		{
			
			if ( transferData instanceof DesignElementHandle )
			{
				return handleValidateTargetCanContainByContainer( targetObj,
						(DesignElementHandle) transferData, validateContainer );
			}
			else if ( transferData instanceof ColumnBandData )