_Scroll
bool _Scroll(const BPoint& cursor);
_Scroll(fScrollTop, fScrollBottom, 1);
_Scroll(fScrollTop, fScrollBottom, 1);
_Scroll(fScrollTop, fScrollBottom, -1);
_Scroll(fCursor.y, fScrollBottom, -numLines);
_Scroll(0, fHeight - 1, fHeight);
_Scroll(fCursor.y, fScrollBottom, numLines);
void _Scroll(int32 top, int32 bottom,
_Scroll(fScrollTop, fScrollBottom, numLines);
return _Scroll(cursor);