HOW TO COMPILE: Run terminal, $ cd to the directory, where the main.cpp is situated, then run this command.
g++ main.cpp -o main pkg-config --libs --cflags gtkmm-3.0
NOTE: is important to use this "`", not this "'" symbols.
Dependencies:
GTKMM library -- http://www.gtkmm.org/en/
( sudo apt-get install build-essential libgtkmm-2.4-dev )