Focus Tracker is a simple app to keep track of how much time an app has the user's focus, potentially helping them better track their time on the computer.

On a Ubuntu 12.04 machine or a similar environment, this should suffice:

sudo apt-get install gir1.2-appindicator3-0.1 gir1.2-wnck-3.0 \
   gir1.2-gtk-3.0 gir1.2-webkit-3.0 python-gi

For an ArchLinux machine:

sudo pacman -S libwebkit3 libwnck3 gtk3 gobject-introspection \
   python-gobject python

Note: The project uses GNOME's GObject Introspection technology (hence the "gi" part in those package names) to enable Python to utilize GNOME's available packages (Ubuntu's AppIndicator, GTK+, ...) so if you happen to run a different distro, just look around for some similar GObject Introspection packages.

From Ubuntu package:

sudo add-apt-repository ppa:ndtrung4419/focus-tracker && 
sudo apt-get update && sudo apt-get install focus-tracker

From source:

git clone https://github.com/lewtds/focus-tracker.git focus-tracker
python setup.py install

If you've installed Focus Tracker:

$ focus-tracker

or look for an entry named 'Focus Tracker' in your favourite app launcher.

Also, there's a run script inside the main package directory under the name of "focus-tracker". Assuming you've downloaded and unpacked the software into a folder named focus-tracker, the following command should runs the app:

cd focus-tracker && ./focus-tracker