Merge pull request #2179 from dopplershift/pylab-switch Enable switching %pylab mode between inline and a single gui mode in a single notebook. With this merge, `%pylab` can be called interactively to toggle inline/GUI (matplotlib floating windows) mode. After initializing `%pylab inline`, now one can call `%pylab` without arguments to activate the default GUI or ask for a specific one as usual. IPython will detect if a different GUI is requested if one was already activated and will refuse to do so (to prevent multiple event loops from running concurrently, which often leads to problems).