This is dumb, and I'm sure I'm just missing the one of the thousands of properties that would make this work, but I'm having trouble modifying the borders on my tree column headers. I have an explicit ColumnSet, and I've tried modifying the following properties of its ColumnHeaderAppearance: BorderColor, BorderColor2, AlphaLevel, BorderAlpha, with no effect. Modifying BorderColor3DBase does have an effect, as do other properties like BackColor, so the problem isn't that I'm just looking at the wrong ColumnSet entirely.

I've also changed the ColumnSet's BorderStyleColumnHeader property to Solid, without any effect.

What am I missing?

Thanks,
   Aaron