Oh, missed that one. If you're comfortable editing XML you can patch this. Find the file symbols.xml in the Mobius application support folder. Bring up the Help->About window and it will show you where that is after "Configuration root:".
Look for this:
<Function name="LoadMidi" level='ui' tree='File'/>
change it to this:
<Function name="LoadMidi" level='ui' tree='File' argumentLabel='MIDI File'/>
