Set a default file extension

It bugs me that I have to manually select the .esf2 format every morning when I save a new file for the day.  I know that there isn't really a difference between an esf2 file and an esf3d file that contains no Augment3d model, but I like to stick to esf2 when I'm not planning on using Augment3d (which is like 99% of the shows I do), and I get a little ruffled when an esf3d file sneaks its way in.

I'd love it if the "save as" dialog defaults to whatever the current file's extension is instead of picking esf3d by default.