In the new configuration window, I think a slightly off icon is shown which suggests you are dragging the whole column, while in fact column dragging is not supported, you are dragging only the vertical bar.



I would have expected this icon (I think this is the default for column resizing in VS2015, but other styles may exist, of course)



Of course, this is a tiny, tiny bug if at all, but thought to report it either way. As an aside, the resizing presently only works on the header bar, but it feels more natural to allow it anywhere down the column line (compare the second animation above, where the cursor is not on the header).

(I'd understand if you have more pressing matters currently ;)