Cross compiling gtkmm on Linux for Windows gives the error "unrecognized option" -pthread "

Question

I am trying to compile a simple "Hello World!" gtkmm provided in the gtkmm tutorial using mingw on Linux to make a Windows executable.

I can execute the executed source code using the following command line: g++ main.cpp -o bin `pkg-config gtkmm-3.0 --cflags --libs` on Linux and everything works fine , but when I try to use i686-w64-mingw32-g++ main.cpp -o bin `pkg-config gtkmm-3.0 --cflags --libs` , it does not show this error:

 i686-w64-mingw32-g++: error: unrecognized option '-pthread' 

Is there something I missed and should be installed before compiling?

And also, is there a neat cross-compilation tutorial (especially about gtk + or gtkmm)? I searched a lot, but there was nothing useful.