fix PBD::ID string format

diff --git a/libs/surfaces/generic_midi/generic_midi_control_protocol.cc b/libs/surfaces/generic_midi/generic_midi_control_protocol.cc
index c13fee0e4f3f4a330fb368c1208bd37c10237618..d70aeaaf48aefefd108480019e3293fd8a552d3e 100644 (file)
--- a/libs/surfaces/generic_midi/generic_midi_control_protocol.cc
+++ b/libs/surfaces/generic_midi/generic_midi_control_protocol.cc
@@ -564,7 +564,7 @@ GenericMidiControlProtocol::set_state (const XMLNode& node, int version)
                                                } else {
                                                        warning << string_compose (
                                                                _("Generic MIDI control: controllable %1 not found in session (ignored)"),
-                                                               id) << endmsg;
+                                                               id.to_s()) << endmsg;
                                                }
                                        }
                                }