No export file type selector on Linux Cinnamon

[jasonculligan]

Linux Mint 22.1. When I select "Export..." I get a standard file dialog, so I just enter the file name but there's no file type extension to indicate what type of exports are supported:

So I then get this message after clicking "Save"...

Now, I must take note of the types and then go back and so it again and manually include the desired and supported file type extension.

It would be better if you include the supported export file types as a selector in the dialog, similar to how you do it in the save and open menu options.

[mb21]

Unfortunately, I had to disable this for Linux in 7a0a933 due to the Electron bug electron/electron#21935

(see #114 (comment) for discussion)