Solution 1:
I only had the normal gtk3 files installed, not the developement files needed for cmake to make use of:
sudo apt-get install build-essential libgtk-3-dev
pkg-config not finding gtk+-3.0
Solution 1:
I only had the normal gtk3 files installed, not the developement files needed for cmake to make use of:
sudo apt-get install build-essential libgtk-3-dev