works as described

This works.

No, it doesn't do even that. Sorry, I only tested that with 3.1.26 which is older than your fix.
No encrypt-only key is offered or selectable for signing any more in Gpg4win-4.2.0-beta360

This works, when sign is selected and no standard OpenPGP key for the mail address exists.

just noticed that restarting the background processes with F5 on the certificate list does not work if the list is empty. (checked with Gpg4win-4.2.0-beta357)

closing this due to external testing. The follow up on this is T6568

This works in so far that the background processes are killed with the restart button. For remaining issue see T6567

works

works

cancelling decryption does not work yet on windows

I'd prefer "Ablauf Hauptschlüssel" as I don't like "Primärschlüssel". But definitely in two words.

ok, then this is resolved

Which is the same URL as the F1 Help page thus probably opened via QProcess?

It works, including the nice message box, for most links in the Help menu, but not for the Kleopatra Handbook.

works

could not trigger it with the described steps on windows

works for 4,1 GB, too.
(Tested with Gpg4win-4.2.0-beta346)

works

works

It does not work as described for subkeys with later expiry dates if the primary key has already expired:

No. I only noticed a difference of the behavior between gpgtar on the cli and Kleo. Ingo said the behavior in Kleo has always been the same, gpgtar an Kleo differ in that. Case was therefore closed for me.

If I understand you correctly, you want to remove the checkbox before "Encrypt to others"?

If you only want to encrypt to one key you could do this without warning if you remove the check before "encrypt to others".

works (at least for small directories)

works:

works

The current date should be avoided even if explicitly chosen, on the command line the earliest allowed date is tomorrow.

Would work better if every attention craving window would refer to the file resp certificate it addresses but that is covered by T6152

The following works, too:

At least the first part seems to be identical behavior to that described in T6488 for USB devices.

Before you ask: I can write on that device and it works with gpgtar on the commandline:

Was resolved, see T4457

closing, as setting a password on a key without password works (at least in current gpg4win version). For improvement of the user guidance see T6436.

In T6473#170380, @ebo wrote:

And when I set the validity to never expire (works) and afterwards set it to a date again, the date is now only set for the main key

Update: This is as designed, see https://dev.gnupg.org/T6473#170299 point one.

works

works, no KIO error. Gpg4win-4.1.1-beta317

Works. The only drawback is: for the message to be displayed in the "for others" part of the encryption dialog you have to click in the next line before it is displayed.
If you click on sign/encrypt directly, you won't see the warning. At least if you select the recipient by starting to type and the selecting from the dropdown.

And when I set the validity to never expire (works) and afterwards set it to a date again, the date is now only set for the main key

The first testcase (with plain testkey Xena) works, both are extended with "change validity". But the expiry day of the subkey is one day later than the date I gave.

And please add a tooltip for "Certify for everyone to see (exportable)", all other options there have one.
Suggestion for the text:

works

works, Gpg4win-4.1.1-beta295

the option works

in gpg.conf

This works, basically.

works now, Gpg4win-4.1.1-beta295

works

works with Gpg4win-4.1.1-beta295

The workaround works.