TextWrangler is my favorite free text editor on OS X. One must-have feature that it has, is rectangular selection (otherwise known as 'column mode') which lets you select text in a vertical rectangle, rather than by line.
I just looked up how to do it yesterday: hold down the Option key as you drag. I tried it. It didn't work. I tried it over and over, thinking there might be some order to holding, clicking, dragging, etc. I looked on-line, I tried it on my laptop's built-in (not external) keyboard. Nothing.
I was filled with rage. Then I realized that I had "Soft Wrap" turned on. As soon as I turned that off, rectangular selections started to work.
Duh. It makes perfect sense. If it's soft wrapped, how does the software know where your selection lies in the text? Change the window size and the text re-wraps, making the selection funny.
I just wish that the docs said that. Jeez. Save me from myself, please.