016c36c917
This issue was revealed during testing for GitHub Issue #875. "ERROR: AddressSanitizer: attempting free on address which was not malloc()-ed", reported by examples/howto-menu-with-images.cxx if the window object was released at the end of the program, causing Fl_Menu_::clear() to be called. The issue was caused by casting all supported label types to 'const char *' which are stored in Fl_Menu_Item::text and then trying to free() all text strings in Fl_Menu_::clear() under certain conditions. Now images and Fl_Multi_Label's are no longer (tried to be) free'd.
README - Fast Light Tool Kit (FLTK) Version 1.4.0
WHAT IS FLTK?
The Fast Light Tool Kit is a cross-platform C++ GUI toolkit for
UNIX®/Linux® (X11 or Wayland), Microsoft® Windows®, and macOS®.
FLTK provides modern GUI functionality without the bloat and
supports 3D graphics via OpenGL® and its built-in GLUT
emulation. It was originally developed by Mr. Bill Spitzak
and is currently maintained by a small group of developers
across the world with a central repository on GitHub.
For more information see README.txt:
https://github.com/fltk/fltk/blob/master/README.txt
