"Unacceptable TLS certificate" warnings could use more detail
Any certificate-related failure to connect to a TLS server using (for example) GSocketClient will result in a GError with an "Unacceptable TLS certificate" message. There are no further hints about why: certificate is expired? signature is wrong? unknown CA?
Some kind of extra hint here, even if only in the message, would be pretty nice. Alternatively, it might be nice if GSocketClient grew an API for reporting details about certificate errors (although that would be a bug against GLib).
(I know it's possible to hook into the GSocketClient "event" signal for the G_SOCKET_CLIENT_TLS_HANDSHAKING event and install an "accept-certificate" handler on the GTlsClientConnection, but this is a convoluted...)