you can find the deb files on https://launchpad.net/ubuntu/+source/gtk+3.0/3.24.20-0ubuntu1/+build/19437463
check on your system the packages from that source using $ dpkg -l | grep 3.24.20-0ubuntu1.1
and download in a new directory the corresponding deb from the webpage, then install them using $ sudo dpkg -i *.deb in the directory where you downloaded
you can find the deb files on https:/ /launchpad. net/ubuntu/ +source/ gtk+3.0/ 3.24.20- 0ubuntu1/ +build/ 19437463
check on your system the packages from that source using
$ dpkg -l | grep 3.24.20-0ubuntu1.1
and download in a new directory the corresponding deb from the webpage, then install them using
$ sudo dpkg -i *.deb
in the directory where you downloaded