Xavier Johnson authored May 29, 2018 and Florian Müllner committed Jun 07, 2018

When middle-clicking an app icon on the Dash, it will always try to open
a new window of that app, even if the app doesn't support multiple
windows. Meanwhile, Ctrl+click on an app will only open a new window if
the app allows it.

This change prevents middle-clicks on app icons from opening new windows
for apps without multi-window support.

Closes: GNOME/gnome-shell#316