tmux 3.2 changed the default 'mouse' option to on — how to keep pre-3.2 behavior across mixed terminals
After upgrading from tmux 3.1 to 3.2, the global mouse option now defaults to on . This means mouse-driven pane resizing, pane selection, and window switching are active even in configurations that never set the option explicitly. The practical complication is that the effect depends on the terminal emulator's support for DECSET mouse reporting sequences (10
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