Question
Is there presently any GUI library that can be used for development in PyPy?
Solution
There is no GUI working with PyPy as of now, except wxPython (blog post). I use web-based UIs for stuff that I do anyway, but that's probably irrelevant.
OTHER TIPS
Gtk+ can be used using the python package "pgi".
https://pypi.python.org/pypi/pgi
pgi is a pure-python library for talking to GObject libraries such as Gtk. It's therefore compatible with both C-Python and PyPy, and since it can use cffi it should be extremely efficient with PyPy.
I have tested this on Linux, it's likely to also work on OS X, I'm less sure about Windows.
If you substutite from gi.repository
with from pgi.repository
in the following tutorial, it should get you started: http://python-gtk-3-tutorial.readthedocs.org/en/latest/