Even if _lines is the same with _screenLinesSize, but i still think modifing...
Even if _lines is the same with _screenLinesSize, but i still think modifing these codes is necessary.
Q. why not to use _screenLines.size()
A. In Screen.cpp
_screenLines.resize(new_lines + 1);
_screenLinesSize = new_lines;
_lines = new_lines;
we can see : _lines = _screenLinesSize = _screenLines.size() - 1, so _screenLinesSize is correct and accurate.