history[currentHistoryLine] = expression; currentHistoryLine++;
AppendHistoryLine(expression);
  public void InvokeCalculation(String expression)  {    history[currentHistoryLine] = expression;    currentHistoryLine++;    AddLinesStatic(48,"In> ",expression);    PerformRequest("Out> ",expression);    ResetInput();    RefreshHintWindow();    focusGained = true;    inputDirty = true;    outputDirty = true;    repaint(0);  }