Nice idea on the default filenames.

What OS are you running? I get a prompt when I try to export and overwrite on Ubuntu 18.04.

Also 18.04.
So it is more complicated

1) Let's say I have a file certificate.pem
a) I selected "ceritficate.pem" and a promt appears
b) I write "certificate" as a filename and click save -> no promt and it gets overwritten (I think DOM first checks if there is a file named certificate, ten ads extension "pem" and overwrites it, it shold first add extension and then check)

2) If for some reason I want more dots in the filename, the thing that is after the last dot gets overwritten, i.e. I write first.second.third as a filename, a file called "first.second.pem" gets written instead of " first.second.third.pem"

Thanks; should be fixed by 6829a1c1b3c577cdd6bc6d206dd52608b0a976ab in 2.13.62.

Thanks. Though there is now another issue: if I save a file as "certificate" (without extension), it gets saved as such. Now when I save another file as "certificate", it alerts me I already have a file like that, but it does not get shown in the file picker (only .dom files are shown. I think either 1) always add the .pem extension or 2) also allow non .dom files to be shown in the file picker.

a couple of another very minor points:

a.1) For the default name, should not it maybe include the Creator and Issuer fields from Preferences>General?
a.2)Also adding the word "leaf" to the "export KDM decription certificate" might make sense.
a.3)And the advanced submenus do not have default names (at least there the leaf/intermediate/root in the filename would make a lot of sense to me).

b) And regarding that, maybe Creator should be set by default to DCP-o-matic if this is to be trusted: https://cinepedia.com/packaging/ ).

c) Oh, and regarding issuer and creator, maybe the followint line in the manual:
With these controls you can set the issuer and creator strings that will be put into the DCPs which you create.
should read something as:
With these controls you can set the issuer (typically you or your organization) and creator (application used to author the DCP, i.e. DCP-o-matic) strings that will be put into the DCPs which you create.

d)And I also believe that the line in the manual
<DCPIssuer> — Creator text to write into CPL files.
should be
<DCPCreator> — Creator text to write into CPL files.

(I hope you also see comments on closed bugs)