Yes, you can select panes and windows with the mouse.

  $ cat ~/.tmux.conf 
  set -g default-terminal "tmux"
  bind-key -t vi-copy 'v' begin-selection
  bind-key -t vi-copy 'y' copy-selection
  set -g mouse on
  setw -g mode-keys vi
  
  set display-panes-time 3000 #3s

My two wishes:

- I wish mouse selecting text didn't select across multiple panes, or all of the blank space in a (zoomed) single pane. ("Anyone? Anyone?")

- I wish the tmux copy buffer ( ctl-b [ select yank ctl-b ] ) would copy into the system copy buffer ( ctl-v ).

Selecting, resizing and scrolling panes as well as text selection works for me on Linux (urxvt) and macOS (iTerm), don't know about windows but I don't see why not. Using mouse on, works very seamless with the "new" mouse on setting these days.