Bug report

Clicking of "save" keeps colons in window title.

Bug summary

Code for reproduction

fig = plt.figure()
fig.canvas.set_window_title("2016-06-01T13:00 start")
plt.show()

When you then click on "save", the suggested file name is 2016-06-01t13:00_start.png. I would prefer 2016-06-01t13-00_start.png or a similar string replacement which is acceptable by the operating system.

Matplotlib version

• Operating System: Windows 10
• Matplotlib Version: 2.0.0
• Python Version: 3.6.0

Installed via conda.