[gnull]

Google search result do this weird trick. When you hover on a link the line at the bottom the your browser window shows the actual URL. But if you do "copy link URL" on it, you get a Google tracker URL in your clipboard.

Couldn't one do the same thing to make users get jpegs when they try to save a wepb? How bad would it be?

[kevincox]

It could be used but this really seems like websites trying to "fix" browser UX. In cases like this where the problem is generic it seems like it is best for the browser to provide the UX it thinks is best for the users (possibly with preferences to allow the user to decide globally without needing to configure every single site).