FLTK (fulltick) is a lean but modern GUI toolkit written in C++ with bindings for Perl, Python, Ruby, Lua and Tcl. It's usable and looks alike on all platforms, provides full internationalization, 3D rendering via OpenGL and an internal GLUT backend, static linking, does not require macros or preprocDessing, still comes with a solid set of widgets, and its GUI designer FLUID.
minor bugfix: and other improvements - test/native-filechooser help display artefact. - MacOS: a crash when closing a fullscreen window. - Accept empty Fl_Pixmap in Fl_RGB_Image c'tor. - MacOS: drawing error when turning fullscreen a window containing a hidden subwindow (error visible with the tabs test program). - MacOS: possible crash when turning fullscreen the scroll test program. - Add a snapshot of known STR's and RFE's (KNOWN_.html). CHANGES IN FLTK 1.3.4rc3 RELEASED: Oct 31 2016. and other improvements. - string truncation in fluid. - MacOS: a small problem where command Quit of the application menu may not work if Fl_Native_File_Chooser is used before any window is shown. CHANGES IN FLTK 1.3.4rc2 RELEASED: Oct 24 2016. and other improvements. - Make sure the "File Systems" menu item of Fl_File_Chooser lists "/" as the first mounted file system (Linux/Unix platform). - Added line numbers to Edit - Show Source Code viewer. - Improved fluid's template handling. CHANGES IN FLTK 1.3.4rc1 RELEASED: Oct 17 2016. New features and extensions. - Added support for Mac OS 10.11 "El Capitan" and 10.12 "Sierra". - Added full support of true subwindows to the Mac OS X platform. Window nesting to any depth is possible. An Fl_Gl_Window window or subwindow can contain Fl_Window's as subwindows. - Fluid now supports external editors See: Edit - GUI Settings - Use external editor. - Added method Fl_Widget::is_label_copied(). - Added methods Fl_Copy_Surface::w(), Fl_Copy_Surface::h(), and Fl_Copy_Surface::draw_decorated_window(). - Added method Fl_Image_Surface::draw_decorated_window(). - Added method Fl_Shared_Image *Fl_Image_Surface::highres_image() to draw into a high-resolution bitmap image (Mac OS X only). - Added support for OpenGL version 3 and later. - Added method Fl_Mac_App_Menu::custom_application_menu_items() allowing to customize the application menu on the Mac OS X platform. - Added 'fluid -u' command-line switch to upgrade fluid files in batch