Interactive plots with show=False

Interactive plots with show=False or with non blocking matlabplot backends can lead to unexpected results.

For instance (here is gist showing this for sample data - https://gist.github.com/bloyl/7f6a7910bf2afce5f198b6233f39416b )

evoked.info['bads'] = []
evoked.plot(exclude=[], show=False)
evoked.info['bads'] += [new_bad_chans]
evoked,.plot(exclude=[],show=False)
plt.show()

This will make 2 figures. the Butterfly plots will be correct, the first will show no bad channels and the second will show the bads chans in red.

However if you select a time range from either plot you will see a topomap created using on the 'good' channels of evoked. This is unexpected for 2 reasons.

1. exclude=[] should use all the channels. Maybe indicating bad channels somehow.
2. in figure 1, the topomap doesn't match the butterfly plot because the data used to make it changed but only the interactive part (the topomap) saw that change.

This is understandably a corner case and not a high priority but I wanted it listed so I don't completely forget about it :)

Start with the linked gist and reproduce the shown evoked.plot(..., show=False) sequence, including the later mutation of evoked.info['bads'] and plt.show(). Trace how the interactive topomap obtains channel state from each figure. Done means non-blocking plots keep consistent data and apply exclude=[] as described.