Stay with Python 2 as a lot of libraries, including PyGtk, aren't compatible to Python 3 yet.
But having a look at the changes in Python 3 to avoid unnecessary incompatibilities may make it easier to migrate to python 3 later.
ClassicMenu Indicator - classic GNOME menu for Unity
Unsettings - configuration program for the Unity
Privacy Indicator - easily switch privacy settings in Unity
Arronax - create and modify app starters
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