When I enable copy mode in a window, I see "Copy mode ..." in the bottom line of the terminal. I configure screen to show the list of windows on the bottom. Now, when I switch to another window and then back to the first window, the notification that I am in copy mode is gone. (And I wonder why a command takes so long, until I press a key, and realize I'm in copy mode.)
So my question is: is there a "permanent" visual indication that a given session is in copy mode?