Ignacio,
Thank you for the list of dev libraries. I had many of them
installed, but the crucial missing one was libgtk2.0-dev - and also
some Gnome libraries that don't matter under Kubuntu. Since Gnome is
based on GTK I had assumed that everything required would be in the
non-development version of these libraries, but my assumption was wrong.
For future reference, it might be helpful to add a note to the text
on Gretl's dependencies advising users to install the -dev variants
of the libraries from the relevant repository. This will always pick
up the standard non-development version if it is not present.
Gordon