gnome-extension for core20 has been used so lot of libraries were not needed. ##changes in facetracker app facetracker is based on opencv tracking APIs. It looks like the tracking abstraction in OpenCV has changed a lot so original sample code from Alfonso's repo
https://github.com/alfonsosanchezbeato/Single_Face_Tracking_using_5_inbuilt_OpenCV_trackers.git
doesn't work. So here I have added facetracker.cpp file. Please replace original repo file with this one so that facetracker will compile.