Not necessarily. At least in Gnome-terminal, Ctrl-Alt-(mouse drag) is a block select that works just fine for copy-paste out of a vertical split. Or do the rot

Not necessarily. At least in Gnome-terminal, Ctrl-Alt-(mouse drag) is a block select that works just fine for copy-paste out of a vertical split. Or do the rotation thing. Or do the copy-mode thing. More than one way to skin this cat; just depends on which workflow you wish to adopt.