The width of the last column header on a horizontally scrolling datagrid

To reproduce:

Create a spark datagrid with more columns than fit in the width of the datagrid. A horizontal scrollbar is shown. You'll see the last column header will wrap when it's scolled in and out of view. It's width changes based on how much of it is visible all the way down to zero. The other columns do not do that. Setting minwidth does not change it.