[Feature request] Fade non-interactable parts when a side-panel is open

[RaiHormo]

I'm not sure if i should be talking about this here or libcosmic, but whenever a side-panel is open, for example the add applet menu, everything behind the side-panel becomes non-intractable without any clear indication.

I would suggest fading out those parts to make it more clear and better separate the side-panel.
Here is a mockup of what I mean: