Bug report

Bug summary
I'm upgrading from 1.3.1 to 2.0.2 and all of my plots work except for those that use blitting
This worked in 1.3.1

calling canvas.blit(ax.bbox)
Fails in the GTKAgg backend _gtkagg.cpp

Easiest example is to use the mpl examples and run pong_gtk example
matplotlib/examples/event_handling>python pong_gtk.py

https://github.com/matplotlib/matplotlib/blob/master/examples/event_handling/pipong.py#L214

Actual outcome
https://github.com/matplotlib/matplotlib/blob/master/src/_gtkagg.cpp#L75
destbufferptr = &destbuffer[0]; fails due to destbuffer being empty

Expected outcome
destbufferptr retrieves a pointer to the beginning of the vector

I have two workarounds

1. Pass None as the bbox
2. Modify _gtkagg.cpp

destbuffer.push_back(0);
destbufferptr = &destbuffer[0];
destbuffer.pop_back();

Matplotlib version

• Operating System: Window2 10 x64 Version 1607 (OS Build 14393.1198)
• Matplotlib Version: 2.0.2
• Python Version: 2.7.8
• Jupyter Version (if applicable):
• Other Libraries:

Build from source