I am using a Windows Forms TreeView control in my program. I would like to allow the user to select multiple nodes at the same level by dragging their mouse pointer around (also called a "lasso" selection). I don't think a standard TreeView allows that.

My question is what would be the best way to achieve this? Do I have to write custom selection behaviour of my own in perhaps a custom or derived control? Where do I start?

I don't need a detailed explanation. Just a small nudge in the right direction.