[altfredd]

What exactly do you want to block here? The user clicked a form control, the form control sent a request to server. It is no different from clicking a link.

You know, that HTTP allows websites to "track" you each time you visit them, right? The horror!

[progval]

It probably works with ":hover" too

[ahje]

Yes, and the twitter link above suggests that this is already used for tracking in the wild.

That being said, if one is THAT worried about tracking then one should not be on the modern web, and should probably stick to using Lynx over TOR.