gtkmm and Win32
One of the major advantages of gtkmm is that it is crossplatform. gtkmm programs written on other platforms such as GNU/Linux can generally be transferred to Windows (and vice versa) with few modifications to the source.
gtkmm currently works with the MingW/GCC compiler with a compiler version that supports C++14, such as gcc 6.2. It also works with Microsoft Visual C++ 2017 or later (including the freely available express editions) on the Windows platform. There is an installer available for gtkmm on Microsoft Windows, but as of this writing (February 2017) it has not been updated for a long time.
Refer to https://wiki.gnome.org/Projects/gtkmm/MSWindows for instructions on how to build gtkmm on Windows.