User-Agent: Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.5) Gecko/20030925 Build Identifier: Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.5) Gecko/20030925 Sorry for the fuzzy report. I think this used to work, say pre 1.5, but can't think of a test case that I know once worked and does not work now. Twice recently (after installing 1.5) I have tried to download Mac software as .dmg files (http://prdownloads.sourceforge.net/opensteer/SteerTest_0_8_macosx.dmg?download (mine) and http://www.sente.ch/pub/software/CVL/CVL.dmg) and I get a dialog saying : The file "xxx.dmg" is of type application/octet-stream (Binary Executable), and Mozilla does not know how to handle this file type... If I choose "Save it to disk" I can go the the finder and open the .dmg file manually (which launches Disk Copy) and all is well. I expected these files to "just open" from Mozilla. Is this a Mozilla problem or a MIME type problem with various servers (including SourceForge?!) like in Bug 194211? Reproducible: Always Steps to Reproduce:

If the server is sending the file as application/octet-stream, then Mozilla prompting you for what do with the file is the expected behavior.

The next package I tried to download had a slightly different symptom which suggests this IS a Mozilla problem. For the file http://www.codefab.com/unsupported/SSHPassKey_v1.1-1.dmg the dialog said: The file "SSHPassKey_v1.1-1.dmg" is of type application/x-disk-copy, and Mozilla does not know how to handle this file type... That seems like a reasonable MIME type, but still Mozilla is flummoxed.

What do you mean by "just open", exactly? Note that "application/x-disk-copy" is a type someone just made up (hence the "x-" prefix), so we just had no way to know it existed...

Yes, there is a widespread lack of mime type support from servers hosting .dmgs (text/plain is popular) but it sounds like what you want is for Mozilla to do the right thing based on the .dmg extension, which is bug 67940, currently WONTFIX. *** This bug has been marked as a duplicate of 67940 ***