The visual component of a scrollbar that moves to indicate your current position within the data. -FW
PT 12-Aug-2003: This is more usually termed the scrollbar thumb.
FW: Hm. While thumb is more common (I just did a Google search comparing them - news to me), I think elevator is Microsoft's term for it (not that they're the authority, but the majority of Tcl coders do use Windows).
RS didn't know either term - for vertical scrollbars, "elevator" tells it quite nicely, but a horizontal one?