In Google Chrome, when I go to an encrypted page that contains unencrypted content, I get the following pop-down, which allows me to either load or not load the insecure content, making a clear recommendation to not load it:
Here, the user is clearly notified that there is a problem and is even provided with a way to stay safe by not loading the insecure content.
In Firefox, when I go to the same page, I receive the following popup dialog, however the page then proceeds to load the insecure content anyway:
However, the above checkbox by default is left unchecked, so most users will only see this once.
In addition, both Opera and Konqueror continue to load the unencrypted content as well. In both of these browsers, the address bar remains white (the same as visiting a normal page), however neither of these browsers even give any further indication to the user that there is a problem with the site unless you manually click to view the certificate details or happen to notice the address bar change (or not change) color.
So my question is, if the unencrypted content is loaded isn't the damage already done? I know this is more a matter of opinion, but why would other browsers not provide a way to prevent this content from being loaded completely? Doesn't this add to security?
Edit: Doing a bit more searching I came across these Mozilla bugs related to this:
So I'm assuming that the reason this is not implemented (at least in the case of Firefox) is because it is a difficult bug to fix, but they are working on it.