Tweak the default choose modes formats:

- Only show pane title if it is not default and not empty.
- Add a prettier time format and use that instead of long ctime().
- Remove clutter and change the order.

window-client.c

@@ -37,8 +37,7 @@ static void		 window_client_key(struct window_mode_entry *,
 #define WINDOW_CLIENT_DEFAULT_COMMAND "detach-client -t '%%'"
 
 #define WINDOW_CLIENT_DEFAULT_FORMAT \
-	"session #{session_name} " \
-	"(#{client_width}x#{client_height}, #{t:client_activity})"
+	"#{t/p:client_activity}: session #{session_name}"
 
 static const struct menu_item window_client_menu_items[] = {
 	{ "Detach", 'd', NULL },