Bug report

Bug summary

shift + w should close all open figures, as outlined in the docs. However, the shortcut does not seem to have any effect. Furthermore, none of the other equivalent -- albeit undocumented -- keybindings as defined in plt.rcParams ('keymap.quit_all': ['W', 'cmd+W', 'Q'],) have any effect either.
This is in contrast to ctrl + w, which is supposed to close a single figure, and does that just fine.

Code for reproduction

fig1 = plt.figure()
fig2 = plt.figure()
# press shift + w

Actual outcome
Nothing happens.

Expected outcome

All figures are closed.

Matplotlib version

• Operating system: Ubuntu, Windows
• Matplotlib version: 2.2.3, 3.0.3
• Matplotlib backend (print(matplotlib.get_backend())): TkAgg
• Python version: python 2.7.13, python 3.7.3
• Jupyter version (if applicable):
• Other libraries:

Ubuntu 17.03 / python 2.7.13 / matplotlib version 2.2.3 from source;
Windows 10 / python 3.7.3 / matplotlib version 3.0.3 via Anaconda (default channel)