Sortir de la boucle à l'appui d'une touche.

bool echap = false;

while (aidecomp < secondesd)
     {
          if(echap == true)
               {
                    break;
               }
          else
                    {
                              Cursor.Position = new Point(posx, posy);
                              DoMouseClick();
                              aidecomp = aidecomp + secondes;
                              System.Threading.Thread.Sleep(secondes);
                              Application.DoEvents();
                    }
     }

public void escapeTest(object sender,KeyEventArgs e)
          {
                    if (e.KeyCode == Keys.Escape)
                    {
                              echap = true;
                    }
          }