Fix file extensions persisting in file dialog after export
Created by: cooperra
This caused issues if one decided to export many formats in a row. The new file extension would be appended to the previous one.
Now, the filename is retained without its extension for successive exports.
Fixes #7291 (closed)
I could use a bit of review for this. I added a field to ProjectExportDialog to hold the filename, but stylistically I don't know where it belongs in the declaration.
Or let me know if there's a more-preferred solution. Thanks!