To reproduce: on Mavericks with Anaconda 2.0.1, python 3.4, Anaconda's default mpl 1.3.1, in ipython:

%matplotlibimport numpy as npimport matplotlib as pltplt.plot(np.random.randn(10000))

This brings the plot up in a window that cannot even be resized.
I made a modified version of ipython the ipython script:

efiring@manini2:~/anaconda/envs/python3/bin$ diff ipython ipythonf1c1< #!/Users/efiring/anaconda/envs/python3/bin/python3---> #!/Users/efiring/anaconda/envs/python3/python.app/Contents/MacOS/python

and with this, the plot seems OK, except that it doesn't always register the "enter" event; when the window is selected, moving the cursor from outside to inside sometimes triggers interactivity (the cursor position is shown when inside the axes), but sometimes it doesn't. Moving the cursor inside more slowly seems to help, but it is not very predictable. This flakiness is confirmed with mpl 1.4.0rc3 using homebrew python3.4 with pip-installed ipython; these now link to the framework build.
I was not successful in building mpl from git in the Anaconda environment; shared libraries were not found. Therefore I have not tested the rc3 with the Anaconda default python 3.4.