Issue description

Steps to reproduce:

• Build and run tmux from master (as of this writing 3934d9b): ./tmux -vv -f/dev/null -Ltest
• Open a menu: ./tmux menu foo '' '' bar '' ''
• Change the font size of the terminal (tested with Terminal.app and Alacritty) using ⌘ +

Expected behaviour:
The terminal font size is increased and all displayed content in tmux, including the menu, remains visible

Expected behaviour:
The terminal font size is increased and the menu is dismissed

@nicm, not sure if this is an issue with the terminals I used or something within tmux.
Getting too late for me to look into deeper this now, so I tracking this here to get the conversation going.

Required information

Please provide the following information:

• tmux version (tmux -V): tmux next-3.4 (compiled from 3934d9b)
• Platform (uname -sp): Darwin i386
• $TERM inside and outside of tmux (echo $TERM): inside: tmux-256color outside: alacritty, xterm-256c
• Logs from tmux (tmux kill-server; tmux -vv new):
  • tmux-client-56613.log
  • tmux-out-56615.log
  • tmux-server-56615.log