uses commctrl; 
 
procedure ArrangeDesktopIcons(wie: integer); 
var 
  h: THandle; 
begin 
  h := getwindow(getwindow(findwindow('ProgMan', nil), gw_child), gw_child); 
  sendmessage(h, lvm_arrange, wie, 0); 
end; 
 
// Beispielaufruf 
procedure TForm1.Button4Click(Sender: TObject); 
var 
  art: integer; 
begin 
  art := LVA_DEFAULT; // LVA_SNAPTOGRID 
  ArrangeDesktopIcons(art); 
end;