Why "Delete" button in "Certificate manager" is disables? Why certificates are prefilled?

[Yuri]

On 01/05/2013 09:45, J.R. Oldroyd wrote:
> The certificate hierarchy for the google.com certificate shows that it
> is signed by the two "Verisign Class 3 Public Primary Certification
> Authority" certificates.
>
> If you uncheck the box for "Trust for verifying web sites" for these
> two certificates, then reload thehttps://google.com  page, the browser
> is no longer able to verify the certificate.

Ok, so there are two certificates in hierarchy for google.com: Verisign 
on top and Thawte on the bottom.
I disabled Thawte. Shouldn't chrome say now that google.com is verified 
by Verisign?
Currently it says: "The identity of this website has been verified by 
Thawte SGC CA."
But Thawte certificate is disabled on my system!
I don't know how can people trust that chrome does the right thing when 
disabled certificate is used for identity verification.

Yuri