New project. Make a new track. Select the track and use any generator, such as white noise, specifying a long enough length that a progress dialog appears. Cancel the progress dialog. Save the project. Exit and restart Audacity. Reopen the project. Orphans! You can also prove a memory leak in a debugger if you put breakpoints at the starts of the two constructors of WaveTrack and the destructor of WaveTrack, and the end of QuitAudacity. Follow steps above, and at exit time, the number of calls to ~WaveTrack is less than the number of calls to the two constructors. SECOND PROCEDURE TO MAKE ORPHANS: New project. New track. Generate sound -- do not cancel. Select all, generate sound again -- this time, do cancel the progress dialog. Undo, so you see one, empty track again. Save. Close. Reopen. The cause of these orphans is different from the first case. The first patch is necessary but not sufficient to fix this.