ui: add the infrastructure to support MT events

Add the required infrastructure to support generating multitouch events.

Signed-off-by: Sergio Lopez <slp@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20230526112925.38794-3-slp@redhat.com>
diff --git a/ui/trace-events b/ui/trace-events
index 977577f..6747361 100644
--- a/ui/trace-events
+++ b/ui/trace-events
@@ -90,6 +90,7 @@
 input_event_btn(int conidx, const char *btn, bool down) "con %d, button %s, down %d"
 input_event_rel(int conidx, const char *axis, int value) "con %d, axis %s, value %d"
 input_event_abs(int conidx, const char *axis, int value) "con %d, axis %s, value 0x%x"
+input_event_mtt(int conidx, const char *axis, int value) "con %d, axis %s, value 0x%x"
 input_event_sync(void) ""
 input_mouse_mode(int absolute) "absolute %d"