Alle sichtbaren Fenster minimieren/wiederherstellen

Const Min_All = 419;
       Min_All_UnDo = 416;

procedure All_Minimize;
Var lngHwnd:THandle;
begin
  lngHwnd := FindWindow('Shell_TrayWnd', '');
  If lngHwnd>0 Then
    PostMessage(lngHwnd, WM_COMMAND, Min_ALL, 0)
end;

Procedure Restore_Minimize;
Var lngHwnd:THandle;
begin
  lngHwnd := FindWindow('Shell_TrayWnd', '');
  If lngHwnd>0 Then
    PostMessage(lngHwnd, WM_COMMAND, Min_ALL_UnDo, 0)
End;