This is a problem we (GitHub) are facing in a big way right now. Google Charts doesn't offer https alternatives, so almost all our users get a big "this site is going to steal all your private information" (mixed content warning). We chose to roll out SSL first, then deal with the hard problem of mixed content warnings (building ridiculous image proxies) later. I think a lot of developers underestimate how big of an…
During the last Velocity conference, one of the last sessions on the last day was a talk from Google guys about how to make SSL faster, because they had recently turned SSL on for all gmail accounts. I asked how they deal with the unlocked icon and warning dialogs for mixed protocol content on the page and the response was that people are so used to the popups and the lock being unlocked, that they (Google) don't con…
But the answer is that permitting mixed content was probably a mistake in the first place, but it's one that we have to live with. The ease of mixing content means that many sites get it wrong (including Google sites, to our shame) and the lack of ubiquitous SSL (again, including some Google sites) imposes that on others.
So, I suppose that `we don't consider it a problem' is roughly correct regarding warning dialogs: the answer is not to mix content. The problem is that it's clearly too difficult to do that. (The inability of networks to cache public resources over HTTPS is also an issue and possibly one which we'll address.)
Lack of SSL on the Chart's API is a new one, but I'll look into it now that I know that it's a problem.
As for the rest of the problem: fixing stuff is hard. Miraculous answers invariably tend to be so only in the eyes of the conceiver. We'll keep plugging away.