I have a Datagrid with four columns. Two of the columns can be turned off (set to zero width). This works great !

I want to set the columns so they aren't in total any wider than the datagrid width. So what I did was set three of the widths, then set the fourth one equal to the datagrid width, minus the widths of the other three. Good in theory, but it doesn't work . Are the columns and datagrid measured differently?

Thank you in advance for your help!