Change the existing client flags for control mode to apply for any

client, use the same mechanism for the read-only flag and add an
ignore-size flag.

refresh-client -F has become -f (-F stays for backwards compatibility)
and attach-session and switch-client now have -f flags also. A new
format "client_flags" lists the flags and is shown by list-clients by
default.

This separates the read-only flag from "ignore size" behaviour (new
ignore-size) flag - both behaviours are useful in different
circumstances.

attach -r and switchc -r remain and set or toggle both flags together.

tmux.1

@@ -947,6 +947,7 @@ The following commands are available to manage clients and sessions:
 .It Xo Ic attach-session
 .Op Fl dErx
 .Op Fl c Ar working-directory
+.Op Fl f Ar flags
 .Op Fl t Ar target-session
 .Xc
 .D1 (alias: Ic attach )
@@ -964,12 +965,30 @@ is given, send
 .Dv SIGHUP
 to the parent process of the client as well as
 detaching the client, typically causing it to exit.
+.Fl f
+sets a comma-separated list of client flags.
+The flags are:
+.Bl -tag -width Ds
+.It read-only
+the client is read-only
+.It ignore-size
+the client does not affect the size of other clients
+.It no-output
+the client does not receive pane output in control mode
+.El
+.Pp
+A leading
+.Ql !
+turns a flag off if the client is already attached.
 .Fl r
-signifies the client is read-only (only keys bound to the
+is an alias for
+.Fl f
+.Ar read-only,ignore-size .
+When a client is read-only, only keys bound to the
 .Ic detach-client
 or
 .Ic switch-client
-commands have any effect)
+commands have any effect.
 .Pp
 If no server is started,
 .Ic attach-session
@@ -1095,6 +1114,7 @@ Lock all clients attached to
 .Op Fl AdDEPX
 .Op Fl c Ar start-directory
 .Op Fl e Ar environment
+.Op Fl f Ar flags
 .Op Fl F Ar format
 .Op Fl n Ar window-name
 .Op Fl s Ar session-name
@@ -1132,6 +1152,9 @@ or
 is given, the
 .Ic default-size
 option is set for the session.
+.Fl f
+sets a comma-separated list of client flags (see
+.Ic attach-session ) .
 .Pp
 If run from a terminal, any
 .Xr termios 4
@@ -1209,7 +1232,7 @@ specified multiple times.
 .It Xo Ic refresh-client
 .Op Fl cDlLRSU
 .Op Fl C Ar XxY
-.Op Fl F Ar flags
+.Op Fl f Ar flags
 .Op Fl t Ar target-client
 .Op Ar adjustment
 .Xc
@@ -1252,12 +1275,10 @@ window, changing the current window in the attached session will reset
 it.
 .Pp
 .Fl C
-sets the width and height of a control client and
-.Fl F
-sets a comma-separated list of flags.
-Currently the only flag available is
-.Ql no-output
-to disable receiving pane output.
+sets the width and height of a control client.
+.Fl f
+sets a comma-separated list of client flags, see
+.Ic attach-session .
 .Pp
 .Fl l
 requests the clipboard from the client using the
@@ -1377,7 +1398,11 @@ or
 is used, the client is moved to the last, next or previous session
 respectively.
 .Fl r
-toggles whether a client is read-only (see the
+toggles the client
+.Ic read-only
+and
+.Ic ignore-size
+flags (see the
 .Ic attach-session
 command).
 .Pp
@@ -4480,6 +4505,7 @@ The following variables are available, where appropriate:
 .It Li "client_control_mode" Ta "" Ta "1 if client is in control mode"
 .It Li "client_created" Ta "" Ta "Time client created"
 .It Li "client_discarded" Ta "" Ta "Bytes discarded when client behind"
+.It Li "client_flags" Ta "" Ta "List of client flags"
 .It Li "client_height" Ta "" Ta "Height of client"
 .It Li "client_key_table" Ta "" Ta "Current key table"
 .It Li "client_last_session" Ta "" Ta "Name of the client's last session"