Hi,
Here is a plugin to display MIDI messages.
If i am not wrong there was nothing to do that, or i spend my time for nothing 
. Anyway, that could be useful if you want to route things you don’t know.
Only the last message is displayed, there is no history or what. And it is supposed to display everything, except the system message content.
Here is the repo: https://github.com/vallsv/midi-display.lv2
I just have a problem with an LV2 output control port. Output + Trigger is not working as i expect. I can set the value, but the host never reset it, at least i do not receive the reset value in the JavaScript side. Anybody knows if it is supposed to work, or if it is a bug?
output triggers are to be reset on plugin’s side, not host side
Oh i see. Thanks.
But in this case i should receive 2 times the change event in the JavaScript side if 2 consecutive run have to output the same value. I have to check but feel like i have to cheat around.
I did some tests. I feel like the Mod do not manage well the triggered output. It is difficult to check, i don’t know hosts supporting that. But i think, as there is, i guess a filter to reduce the amount of events in the JavaScript world, it is mostly impossible to receive the right output trigger. It is mostly always zero.
For triggered output, the JavaScript change event callback should not receive the last value of the port, but at least, the last value during the integration period which is not the default value (else the default value). It is still not perfect, but can be much better.
Do you know the way it behave? or where is the code?
I still can change the way i manage this thing in the plugin, from event based, to state based. What do you think?
This looks great for some debugging and figuring out which messages are being received!
When can we expect it in Beta? 
Btw managed to build and install using mod-plugin-builder and seems to be working great.
One feature request though: add a mode that allows for actually seeing what musical notes or GM-drums are being sent. This could be useful when one is playing with the sequencers.
Hey @dreamer, I just confirmed with the team and the MIDI display may be pushed to the Beta plugins really soon (probably today).