message: Fix wrong rendering of EditingArea on macOS
  The horizontal separator lines didn't fully connect to the right-side
  sidebar, there was a half-point gap.
diff: @@ -557,7 +557,10 @@ EditingArea::~EditingArea()
  void EditingArea::OnPaint(wxPaintEvent&)
  {
  wxPaintDC dc(this);
  - auto width = GetClientSize().x;
  + auto width = dc.GetSize().x;
  +#ifdef __WXOSX__
  + width += 1; // correct for half-pixel undrawn part on the right side
  +#endif
  const int paddingTop = MACOS_OR_OTHER(dc.GetContentScaleFactor() > 1.0 ? PX(5) : PX(6), PX(6));
  const int paddingBottom = PX(5);
  