In general, I question the usefulness of the tool tip for the certificate list. The information in the table is already very detailed and for more details there's the details view. Important information that's missing in the table shouldn't be hidden in the tool tip.

Idea:

• For the certificate list it might make sense to have column-specific tool tips, e.g. to give details on "not certified" in the "User IDs" column. For the fingerprint column (just to pick one example) a tool tip makes little sense.

Some guide lines:

• The tool tips of the key list model are used for different UI elements (certificate lists, drop-down, input field). Different UI elements may need different tool tips.
• The tool tips shouldn't be too verbose. Remember that they may be read by a screen reader.
• The tool tips shouldn't duplicate information that's already displayed in the certificate list, e.g. "Valid from/until", "Key ID", etc.
• The short key ID shouldn't be used anywhere. Even the 64-bit key ID should be avoided.

For the certificate list it might make sense to have column-specific tool tips, e.g. to give details on "not certified" in the "User IDs" column. For the fingerprint column (just to pick one example) a tool tip makes little sense.

IMO the User IDs column is the only column where a tooltip makes sense.

I'm a bit undecided about keeping a tooltip for the Name column. As it's at the moment, it contains a lot of duplicate stuff. Just showing a list of the user ids there would make sense. It would be a good chance to remove the mechanism for configuring tooltips