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Well, there is not much documented about it and quite frankly, I never use this view as the Log view is much more useful. However I believe when it is red with a lighting bolt it means that one or more translators is currently processing a MIDI message.
I tested this by having my controller as input device and a virtual port as my outgoing device and setting up a single translator. When the translator is active, I see the MIDI In blink, the blue MIDI connector turns red with a lightning bolt and MDI Out flashes.
However if I turn of the translator and use a MIDI route instead, the Router Out flashes and the blue connector in the middle does nothing (if the translator is disabled).
Again, I generally use the Log Window as it provides much more detail on what is going on than the Event Monitor which only shows that “something” is happinging but not much information about it.
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