For me (OSX 10.10.2, Matplotlib 1.4.3), what works is changing the matplotlib backend to TkAgg. Before importing pyplot or anything, go:
import matplotlib
matplotlib.use('TkAgg')
Plot windows now pop-up, and can be Command-Tab'ed to.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…