begin_reversible_command (_("add tempo mark"));
XMLNode &before = map.get_state();
map.add_tempo (Tempo (bpm,nt), requested);
XMLNode &after = map.get_state();
session->add_command(new MementoCommand<TempoMap>(map, &before, &after));
commit_reversible_command ();
begin_reversible_command (_("add tempo mark"));
XMLNode &before = map.get_state();
map.add_tempo (Tempo (bpm,nt), requested);
XMLNode &after = map.get_state();
session->add_command(new MementoCommand<TempoMap>(map, &before, &after));
commit_reversible_command ();