After landing Bug 574688,
lock icon(security-button) is missing.
The lock Icon indicates security level of https page.
I think it is important inforemation.
It should be indicated somewhere.
If it will be displayed, it should be displayed in urlbar with playing the current https notification somehow.
To repeat myself from another unrelated bug, but on this same topic:
Simple version: ALL PADLOCK ICONS MUST DIE!
Padlock icons to way too many people imply safety. They really just were used to indicate a stable encryption link. You can be fully encrypted to either your bank, or criminals pretending to be your bank who wish to steal all your money.
It was decided quite a while ago to phase them out. I think the only one eventually being allowed to stay is in the popup pane when clicking the identity button for an encrypted page. The identity button and its styling (blue SSL / green EV) is the replacement for the lock as well as that old yellow background we used to have.
As to the information provided by clicking the lock icon in the status bar, it opens the same thing as the "More Information" button in the identity button popup pane, so there is no loss of functionality, just old confusing UI.
Closing as INVALID by intended gradual phase out of this old misunderstood feature.