对于ScrollBar,PageSize就可以了,对于其他的,下面的也许适用,摘自TScrollBar.SetPageSize;
procedure TForm1.Button1Click(Sender: TObject);
var
ScrollInfo: TScrollInfo;
begin
ScrollInfo.cbSize := SizeOf(ScrollInfo);
ScrollInfo.nPage := StrToInt(Edit1.Text);
ScrollInfo.fMask := SIF_PAGE;
SetScrollInfo(ScrollBar1.Handle, SB_CTL, ScrollInfo, True);
end;