Today I discovered that my
gnome-shell doesn't let me run commands using Alt+F2 anymore. Both keys are now bound to the activity view, just like the left super key (Super_L).
The Show the run command prompt preference in the keyboard shortcuts system panel is already set to Alt+F2, but this seems to make no difference.
As a result I have no way now to invoke the command prompt for the shell and I wonder if somebody else has the same problem.
I stumbled into this weird behavior trying to configure the right Super key to work as the left one and open the activity view. That effect proved impossible to achieve and Super_R keeps doing nothing for me.