How to install meld 3.11 in Ubuntu 14.04?

#Make a clean working directory
mkdir -p work/crap
#Get in to that directory
cd work/crap
#Clone git head
git clone https://git.gnome.org/browse/meld
#Get in to that project directory
cd meld
#Install dependencies
sudo apt-get install intltool itstool gir1.2-gtksource-3.0 libxml2-utils
#Install meld
sudo python setup.py install

If you wanted to work on the code itself without re-installing, I typically do that by installing in a venv and opening the installed to folder in the venv in an IDE.

Result of running meld in a terminal after those steps:

Note that the current version of meld requires GTK+ 3.14, which is not available on Ubuntu 14.04 (Meld requires GTK+ 3.14 or higher. error). So for Ubuntu 14.04, you need to checkout the last version that does not need GTK+ 3.14. That is the meld 3.14.* branch (currently 3.14.3), so checkout the branch using git checkout meld-3-14.