In 0.4.15, cancelling an export (single or multitrack) doesn't stop exporting the track being exported at the time. Which means the engine still is connected to the output file, even if the export dialog closes.
This is because once a ProjectRenderer has been popped from the vector there is no pointer to it outside popRender(). This patch adds that missing pointer.
Moved to pull request #35 at Github
Closed as fixed in the above git hub pull request.