Is this through tmux’s mouse mode? Can you select three lines of only the left side of the session? Does this also work in vim and other places that draw soft boundaries on the screen?
I just tried this in kitty and it didn’t work
I just tried this in kitty and it didn’t work
IMO this setting belongs with the application, and especially with tmux and nvim supporting this natively, you don't really need the terminal itself to implement some potentially fallible heuristic. For example with iTerm if you accidentally drag outside the pane boundary, the selection immediately expands to include both the panes, which is not ideal.