Listview designtime column resize

How come sometimes you can edit the column header size of a listview control at designtime (visually with the mouse I mean) and other times you can't? What changes to make it uneditable?

It seems if I add a listview control and give it some columns in detail view I can then resize them, but if I close the IDE or (not sure what) then I can't anymore, except through the Width property in the Listview Columns property page thing. Whats up with that? I was happy to see that you could change it visually at designtime but then I went to make a change and couldn't anymore and got confused.