There’s a big fight now on the Chimera mailing list about how it should handle missing MIME types. The standards people say that it should treat a file as text and display it in the browser window if there’s no MIME type.
I find myself in the other camp. The browser should do the most reasonable thing even if it doesn’t follow standards. I agree with the people who say it should follow extension mapping if there’s no MIME type. When I click on a .DMG file on a mis-configured server I don’t want it to be displayed in the browser window – I want it to be downloaded to disk. Almost all of the .DMG files I click are OSX disk images. If someone has a different kind of file with a .dmg extension, they should make sure the web server is configured for the correct MIME type. Displaying a disk image in the browser window is NEVER the right thing to do, even if that’s what the standards suggest. Just because the web server is misconfigured, it shouldn’t inconvenience the user. The web browser should try to provide the most pleasant browsing experience, whether or not it follows standards 100%.