Ingrid's piano playing

It has already been said that Leslie Howard's violin pseudo-playing was terrific, but what about Ingrid's piano playing? I think she did a fantastic job, too. Surely she wasn't really playing? Anyone know anything about that?

Edited to add:
Just found this on Wikipedia-

The musical duets, with Howard and Bergman, were dubbed for the soundtrack with professional musicians; however, the actors' hands show the actual music being played: Ingrid Bergman plays the full piano parts (for Edvard Grieg's "Concerto in A minor" and Christian Sinding's "Rustle of Spring"), so her hand positions are correct for the music soundtrack; Leslie Howard could not play the violin, but Ingrid Bergman explained the trick used in the Swedish film: 2 violinists held the bow & violin before Howard in closeups (one held the bow and the other held the violin), while Howard kept his arms at his sides.