Is there a way to indicate mouse reporting status in status line?

[blackbit42]

I recently developed a desire to indicate a couple of tty states in my tmux status line.
The 'alternate screen' (CSI 1049) being active or not is rather straight forward:

set -g window-status-format '#W#F#{?alternate_on,A,}'
set -g window-status-current-format '#W#F#{?alternate_on,A,}'

Another state I am interested in is 'mouse reporting' - at least that is what i think I am interested in.
What I know:

• "It" is influenced by set -g mouse on
• "It" is influenced by e.g. VIM set mouse=a
• When "it" is active, clicking and dragging inside the terminal window does not mark the area by means of the terminal emulator. I can still force that though. I use urxvt, there I must depress the shift key before clicking and dragging.

What I do not know:

• What the mechanism is that is being used. Is it a CSI thing? A ST thing? I am not educated enough on terminal internals to know
• The 'FORMATS' section of the tmux.1 man page has a couple of mouse-related entries, though I do not understand the details.

       mouse_all_flag                  Pane mouse all flag
       mouse_any_flag                  Pane mouse any flag
       mouse_button_flag               Pane mouse button flag
       mouse_hyperlink                 Hyperlink under mouse, if any
       mouse_line                      Line under mouse, if any
       mouse_sgr_flag                  Pane mouse SGR flag
       mouse_standard_flag             Pane mouse standard flag
       mouse_status_line               Status line on which mouse event took place
       mouse_status_range              Range type or argument of mouse event on status line
       mouse_utf8_flag                 Pane mouse UTF-8 flag
       mouse_word                      Word under mouse, if any
       mouse_x                         Mouse X position, if any
       mouse_y                         Mouse Y position, if any

As an experiment, I did this:

set -g window-status-format '#W#F#{?alternate_on,A,}#{?mouse_all_flag,m,}#{?mouse_any_flag,M,}#{?mouse_sgr_flag,s,}#{?mouse_standard_flag,S,}#{?mouse_status_line,t,}#{?mouse_status_range,T,}#{?mouse_utf8_flag,u,}'
set -g window-status-current-format '#W#F#{?alternate_on,A,}#{?mouse_all_flag,m,}#{?mouse_any_flag,M,}#{?mouse_sgr_flag,s,}#{?mouse_standard_flag,S,}#{?mouse_status_line,t,}#{?mouse_status_range,T,}#{?mouse_utf8_flag,u,}'

When I start vim with set mouse=a, I get an M and an S, hence mouse_any_flag and mouse_standard_flag.
Though, when I start tmux with set -g mouse on I do not get either m, M, s, S, t, T or u.

I would have expected that tmux set -g mouse on would cause one or several of these flags to be 1, but that's not the case.
Also, I do not understand what vim causing both mouse_any_flag and mouse_standard_flag actually means.

Long story short, I don't understand terminal mouse 'stuff'.
If somebody could shed some light on this, it would be greatly appreciated.

[nicm]

All the _flag ones relate to the pane, so whether vim has enabled the mouse.

If you want to see if tmux has the mouse turned on just check the mouse option, so #{mouse}.

[blackbit42]

Right...
What I would like to indicate in my tmux status line is a bit more abstract, I think.
I would like to see if 'something is capturing mouse events before they reach my terminal emulator', I guess.
So, would that be a logical OR between any of these?

• #{mouse}
• #{mouse_all_flag}
• #{mouse_any_flag}
• #{mouse_sgr_flag}
• #{mouse_standard_flag}
• #{mouse_status_line}

[nicm]

Nothing in tmux can tell you if something is capturing mouse events before they reach the terminal emulator (or tmux) because it doesn't know.

If you want to know if tmux has the mouse turned on, use mouse.

If you want to know if vim inside tmux has the mouse turned on, use mouse_any_flag.

[blackbit42]

It seems like this actually does what I want:

#{?#{||:#{mouse},#{mouse_any_flag}},M,}'

[nicm]

Different mouse modes are described here https://invisible-island.net/xterm/ctlseqs/ctlseqs.html#h2-Mouse-Tracking

mouse_any_flag is set if any mouse mode has been requested so that is probably the only one you need.

mouse_standard_flag = VT200 mouse (1001)
mouse_button_flag = button events (1002)
mouse_all_flag = all events (1003)

And mouse_sgr_flag (1006) and mouse_utf8_flag (1005) can be set on top of those and change the format of the sequences, they don't change which events are sent.