Bug report

Bug summary

When using MatPlotLib with the TkAgg backend on Ubuntu 18.04, with either Python 2.7 or 3.5, plots are not displayed instead a window that is completely black is displayed.

Code for reproduction

import matplotlib.pyplot as plt
plt.plot((1,4,6))
plt.show()

Actual outcome

The window pops up, except no plot is displayed instead the plot window is just completely back.

Expected outcome

A simple chart of a line-graph going from 1 to 4 to 6. Works on Ubuntu 12, and windows, same versions of MatPlotLib

Matplotlib version

• Operating system: Ubuntu 18.04 running on an Odroid C1+, the Ubuntu 12 version worked previously on the Odroid C1+
• Matplotlib version: Tried three versions, the one from apt-get install python3-matplotlib, the one from pip and the latest revision from this git: a3e2897
• Matplotlib backend (print(matplotlib.get_backend())): 'TkAgg'
• Python version: 3.5.2 or 2.7.15
• Jupyter version (if applicable):
• Other libraries: None