FLTK-1.3.8 [released 20th Nov 2021] FLTK-1.3.8 is basically FLTK-1.1.10's API with extra features and better support for macOS (High Sierra .. Big Sur on the new Apple Silicon (M1) processor) and high resolution displays. These new features include: new Fl_Copy_Surface, Fl_Image_Surface, Fl_Tree, Fl_Table and Fl_Native_File_Chooser widgets; additional methods for dealing with clipboard and system event notifications; printing support; a device abstraction layer; and a new progamming manual generated from the code using Doxygen.

FLTK-1.3.8 includes full UTF-8 Unicode support and can render the glyphs for any UTF-8 supported language if the correct fonts are also installed. Languages which are rendered left-to-right and use standard Latin, Greek and Cyrillic characters are handled out-of-the-box, and simple right-to-left rendering works, but could be improved.

FLTK-1.3.8 does not include a text rendering engine for composing complex scripts. Users of languages requiring composing characters (such as Arabic, Hebrew, and the Indic scripts) will need to work with their own text layout engines using ICU or Pango or whatever.

FLTK-1.3.8 and all previous 1.3.x versions use the same API as FLTK-1.1.10 and those features which change the ABI between versions are wrapped in so-called ABI guards in the library code. The appropriate ABI version can be specified with 'configure', CMake, or by editing a supplied file when using the bundled IDE projects. Most code written for FLTK-1.3.x should work without further modification, but old code written for FLTK-1.1.10 will need to be recompiled to work with FLTK-1.3.8. See the documentation in README.abi-version.txt for more details.