This can be used as a template for any other project.
That is, I declare this (and only this) commit as Public Domain.
But of course, you are free to refer my code, learn, and implement
your own with whatever license you wish (though GNU [A]GPL3+ is always
prefered)

Please note: the menus.ui actions are not configured. If you see a
Quit Application menu, it is done by the window manager (or gnome-shell).

To enable debugging symbols, you can run:
CFLAGS='-O0 -ggdb' ./autogen.sh

To install, you can do 'make && make install' (sudo will be required
for 'make install' if install path (--prefix) can be modified only by
root)

You don't require to run 'make && make install' all the time you change
the source code (or ui files), which is really slow.
You can simply run 'make install-binPROGRAMS' from 'src' subdirectory
(sudo will be required if install path can be modified only by root),
which will compile all the modified files and install in a single step.