• Your Windows build number: (Type ver at a Windows Command Prompt)

10.0.18890.1000

• What you're doing and what's happening: (Copy & paste specific commands and their output, or include screen shots)

I routinely use mouse mode in tmux with WSL for window selection, pane resizing, and scrollback, enabled in tmux.conf thus:

  # -- mouse support ---------------------------------------------------------                                                                                                                                                                                        
  # Enable mouse control (clickable windows, panes, resizable panes)                                                                
  set -g mouse on

While this works perfectly in conhost, it does not work at all in Terminal; nothing happens, as if the mouse events were never reaching tmux.

• What's wrong / what should be happening instead:

tmux mouse support (and presumably other mouse-supporting applications) should work as they do in conhost.