The password dialog (titled pinentry-qt) for the private key (PGP and S/MIME) displays the information of the chosen certificate in a more or less raw format.
This format would be OK for users who are familiar with certificates.
But having more than one certificate it is difficult to directly notice the relevant information.
And for people who are not familiar with certificates the displayed information are very "uncomfortable".


Reproducible: Always

Steps to Reproduce:
1. send an encrypted or signed email with a password protected private key
2. have a look at the password dialog

Actual Results:  
the raw subject and some additional information like validity are displayed in a floating text format

Expected Results:  
show a dialog with the most important information on separate lines, like:
- Common Name (CN)
- Email-Address (EMAIL)
- Optionally additional Email-Addresses (SubjectAltName)
- Valid until (in localized format?) or an icon showing the validity status
- A link to the raw certificate information would be also nice


Alternatively there could be also a dialog showing the "expected result information" of the certificate, before the password dialog opens up.
This could be also useful to choose a certificate, if there are two or more possible certificates for the requested action.