patch 8.0.0030
Problem:    Mouse mode is not automatically detected for tmux.
Solution:   Check for 'term' to be "tmux". (Michael Henry)
diff --git a/src/os_unix.c b/src/os_unix.c
index 107a474..8b0dd55 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -2261,6 +2261,7 @@
     return (name != NULL
 	    && (term_is_xterm
 		|| STRNICMP(name, "screen", 6) == 0
+		|| STRNICMP(name, "tmux", 4) == 0
 		|| STRICMP(name, "st") == 0
 		|| STRNICMP(name, "st-", 3) == 0
 		|| STRNICMP(name, "stterm", 6) == 0));
@@ -2324,6 +2325,7 @@
     return (   STRNICMP(name, "hpterm", 6) == 0
 	    || STRNICMP(name, "sun-cmd", 7) == 0
 	    || STRNICMP(name, "screen", 6) == 0
+	    || STRNICMP(name, "tmux", 4) == 0
 	    || STRNICMP(name, "dtterm", 6) == 0);
 }