Can't open midi device more than once?

Apparently, if you have a midi device connected to your machine, only one piece of software can open it at a time.   I'm trying to testi out the piano roll component in the JuceDemo and had Reaper open to play sounds when i press the keys. If I boot the JuceDemo first, I can see the key presses, but Reaper says "The following MIDI inputs could not be opened: " and then the name of my controller.   If I boot up Reaper first, then the JuceDemo doesn't read the midi input.   

I'm not sure if this is a JUCE bug, a Windows 8.1 bug, or what.  


edit: It seems to be a juce bug, as I'm able to run Reaper and FM8 Standalone simultaneously.   in FM8 options, it says it is using the WASAPI (Shared Mode) for the audio device.   Perhaps JUCE isn't using Shared Mode when it opens a midi device on windows?  

It's a Windows thing. Lots of old Windows MIDI drivers only allow a single client. Nothing we can do about it from the application side.

How can it be a windows thing, if I'm able to open the Reaper DAW and FM8 Standalone and trigger them both at the same time from my Kronos using the Korg device driver?     Seems like a JUCE thing

There's only one API for opening a MIDI device in win32 - by calling midiInOpen(). All apps will call this and AFAIK there's nothing else that the app can do to specify exclusivity.

If it's a Korg driver then they'd be the best people to ask about what's going on, I think.