procedure AllWindows(minimize:Boolean);
var
  hwndx:HWND;
begin
  hwndx := FindWindow('Shell_TrayWnd',nil);

  if hwndx <> 0 then
  begin
   if minimize then
      PostMessage( hwndx, WM_COMMAND, $019F, 0 )
      else PostMessage( hwndx, WM_COMMAND, $01A0, 0 );
  end;
end;