Question / Help [SOLVED]Can someone explain Alt-Cropping to me?

[coolwithpie]

I know this is a stupid question, and I'm going to hit myself once it's explained to me. I just don't get how to alt-crop.

EDIT: Never mind, I'm an idiot. You alt-drag the edges on the image.

 

[Sir]

Hey, if you didn't post this, I wouldn't have known this feature existed. So thanks!

 

[Nataka]

Yeah thanks :D