Macbook App specific midi control

[BobEagleRadio]

I have a MacBook and an external Midi controller which I use to control a specific Music app. The way it works is that I use Command Post app to get the midi button to produce a keyboard combination which then feeds to the app. That's fine as long as the app is on top. But if it isn't then the mid button doesn't work. Is there a way of assigning the midi controller so that even if the app is not the top window the midi button will still cause the app to respond.