How to map 'enable/disable MIDI' button to MIDI controls?

In Ardour 3.1, most buttons in the mixer window are mappable to MIDI controls via ctrl+middle click, including ‘Mute’. The ‘Enable/Disable MIDI input’ isn’t though - is there another way to map it, or is this intentional, or a bug?

This is an important button to be able to control via MIDI as it would allow switching between tracks from a midi keyboard, for instance, without having to use a mouse to switch it in Ardour.


@samtuke: not currently possible.