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
else if ( content instanceof DesignElementHandle )
		{
			child = (DesignElementHandle) content;
		}
		if ( child != null )
		{
			for ( int i = 0; i < handles.length; i++ )
			{
				if ( content == handles[i] )
				{
					continue;
				}
				
				if ( child == handles[i] )
				{
					return true;
				}
				if ( handles[i] instanceof DesignElementHandle )
				{
					
					if ( child instanceof CellHandle
							&& handles[i] instanceof ColumnHandle )
					{
						if ( isInSameColumn( new Object[]{child, handles[i]} ) )
						{
							return true;
						}
						continue;
					}