Comment 9 for bug 1760316

To be clear:
the existing COs are fine for their purpose (focused effect and show focus) and I'd neither extend nor alter them.
'show_focus' for collapsed FX units is disabled by default in the MAPPINGS, and then it's only allowed when parameters are visible which is fine because it reduces mistakes during FX handling in most use cases.

On the other hand, 'focused_unit' would be a GUI helper which should work indepently from individual mappping preferences as it would be activated components-js. It could also be a life saver in case the the user switched the focused FX unit by accident. A bit like a highlight CO for controller decks 1/3 and 2/4.