gtkmm is the official C++ interface for the popular GUI library GTK+. Highlights include typesafe callbacks, widgets extensible via inheritance and a comprehensive set of widgets. You can create user interfaces either in code or with the Glade Interface Designer, using libglademm. Here's an overview, with documentation and status. gtkmm is free software distributed under the GNU Library General Public License (LGPL). C++ (pronounced see plus plus) is a general-purpose computer programming language. ... GTK logo Initially created for the graphics program the GIMP, the GIMP Toolkit â abbreviated as GTK+ â is one of the two most popular widget toolkits for the X Window System, intended for creating graphical user interfaces. ... Glade Interface Designer is a Visual Basic–like graphical user interface creator for GTK+, with additional components for GNOME. Unlike VB, Glade is programming language–independent, and thus does not produce code for events, but rather an XML file, and optionally one or more C-language files that programmers insert... Free software, as defined by the Free Software Foundation, can be used, copied, studied, modified and redistributed. ... GNU logo The GNU Lesser General Public License (formerly the GNU Library General Public License) is an FSF approved Free Software license designed as a compromise between the GNU General Public License and simple permissive licenses such as the BSD license and the MIT License. ...
All gtkmm design decision were publicly discussed at length, and some were still wrong (like the memory management issue) mainly because none of the people involved in the discussion was actually using gtkmm to create an actual application.
gtkmm itself has Glib::ustring, I see that you made its interface similar to std::string, and I also think it's a bad idea, because no matter how standard it is, it's not very convenient nor powerful.
I'm not sure about gtkmm being a "better role-model" for C++ students, but your saying "you'll love gtkmm if you love C++" is the core of the problem, and the reason you still fail to understand why Qt is better.