In Midnight Commander, how to quickly set the right panel to the same directory as the left panel (and vice versa)?
Newer versions of Midnight Commander use Alt-o (also ESC followed by o) to do this.
Older versions used Alt-o for doing a change directory to the currently highlighted directory, so it will depend on which build you are using.
AltO opens the directory your cursor is on.
AltI opens the active panel's directory on the other panel.
Tested on MC 4.7