You are doing it too hard way. There are no need for downloading anything by hands. Installing mypaint and upgrading existing packages is enough. On Maemo5 we have python-gtk2 -2.12.1-6maemo10 which is enough to run Mypaint. Check do you have that version. (e.g. apt-cache policy python-gtk2) And then post exact error message. It contains row numbers and they can give hints what is happening.