In Windows, I can right click on a MIDI file and select Open With … Cubase. No problems (other than seeing a dialog box asking what directory I need to be in).
But when running Cubase, even with no projects open, File/Open will not accept a MIDI file as a valid selection.
If I can do it in one place, it seems I should be able to do it in both places. Any reason why things don’t work this way?
you also cannot open a .cpr from outside of cubase ie. desktop shortcut. these basic OS type functions dont seem to be implemented properly in c8.5. hopefully we will see a bugfix update soon 
cheers
I can. 
Never had a problem with that.
The only struggle was which version it opened with, but I’ve since learned how to deal with that from here in the forums.
Works fine here, find a midi file, right click, open with Cubase 8.5. Cubase opens, asks for a project location, and opens the project with the midi tracks assigned to Halion Sonic SE.
If Cubase is open, You have to use Import/Midi File as always.
.cpr opens Cubase and the project when double clicked, if Cubase is open it asks if You want to activate the project.
You can also just drag it into an open project.
FYI, the not being able to open a cpr file from windows only effects some systems. But is an acknowledged bug.
This thread got sidetracked. Are you talking about dragging a MIDI file or a project file? My question was about opening a MIDI file (never tried opening a cpr file with right-click from the desktop).
The advantage of opening the MIDI file directly is that you get the tempo track. If you import a MIDI file, you must jump through hoops to get the tempo data along with the rest of the note data. I seem to recall that when dragging a MIDI file to a project, you do not get the tempo data, but that recollection may be faulty.
Yes a midi file (hence the FYI regarding the cpr). I suppose the reason it wouldn’t import the tempo is to avoid messing up the tempo of an already existing project.
So your only option to get the midi & its tempo is to use right-click, open with. Although you might try changing the default application for .mid files to Cubase so double clicking would open it if you want to open midi more often in Cubase than a media player. However that might not currently work, until they fix the double click cpr problem (oops, it might be relevant after all).