I posted this information in reply to another topic, but I think it deserves its own topic, so I am posting it in this new topic and adding some additional information . . .
Several years ago, I tried to find a MIDI file editor for the Mac but did not find one, which could have been due to using the wrong search keywords, but recently I found this MIDI file editor for the Mac, and it does most of what I think a MIDI file editor should do . . .
[NOTE: MidiKit 3.6 costs $14 (US) and runs nicely in Mac OS X 10.8.4 (Mountain Lion) . . . ]
MidiKit 3.6 for Mac (Mixage) -- MacUpdate

MidiKit ~ Detail MIDI Data Window
MidiKit does not appear to allow editing what it calls the "Frame" and "Ticks" fields, but I can edit these fields with UltraEdit (IDM Computer Solutions), which is available in a Mac version and is an excellent editor for having a bit of FUN with otherwise incomprehensible binary data files.
UltraEdit has the ability to color-code various programming languages--including XML--which helps to avoid mistakes when using it to input data or to examine an existing file . . .
UltraEdit (IDM Computer Solutions)
Lots of FUN!
