Method SetHorizontalScrollbar

src/ProjectWindow.cpp:481–487

      if (IsWindowValid(mwWindow)) mwWindow->SetHorizontalThumbPosition(viewStart);
   }
   void SetHorizontalScrollbar(int position, int thumbSize,
      int range, int pageSize, bool refresh) override
   {
      if (IsWindowValid(mwWindow))
         mwWindow->SetHorizontalScrollbar(
           position, thumbSize, range, pageSize, refresh);
   }
   void ShowHorizontalScrollbar(bool shown) override
   {
      if (IsWindowValid(mwWindow))