So, I'm trying to decrease the opacity for unfocused windows, with some rules for some specific applications to have some different unfocused opacity than the catch all rule.

I first tried to edit the settings for Translucency under desktop effects, with a rule set in window rules for the specific application, in particular the inactive opacity. This didn't work, it seems that the desktop effect takes precedance over the rule.

I then deactivated translucency, and created a new window rule with Window class set to unimportant so it would apply to all windows, with active opacity at 100% and inactive opacity at my value. There is an additional rule with different inactive opacity loading before the catch all for the specific application.

This works, but it has the unintended consequence of also lowering opacity for the panel, which I don't want. This doesn't go away upon mousing over the panel, implying that it is always unfocused.

My question is, is it possible to set a window rule for the panel to override this? If so what is the window class? If not, is there another way of achieving what I'm after?

How to set opacity for kde panel, how to create window rule for kde panel.

I solved my own problem, the window class of the kde panel is plasmashell, and arbitrary window classes can be found with detect window properties under the create new rule interface