name of click-to-expand widget

This is kind of a strange question,开发者_运维技巧 but what is the name of the widget that you can click on to show/hide content? Usually they have a triangle that you click on and it changes orientation. It is a pretty simple widget to write, but a few days ago somebody told me the generic name, and for the life of me I can't remember what it is called. Does anyone know what I'm talking about?

Twisties, otherwise known as “Disclosure Triangles”