xfce: "whiskermenu" (panel) as well as "xfce4-popup-whiskermenu" are not working

[novoid]

As of 2023-08-03 with commit https://github.com/novoid/nixos-config/tree/e4e4795d464611e13fc8ffbc9a6f6822d1e1986b the installed whiskermenu (package xfce.xfce4-whiskermenu-plugin installed via homemanager/xfce.nix) tool is not working.

I may call it in zsh to show its version/help but it never opens up any GUI element when, e.g., involved via xfce4-popup-whiskermenu -p

When I try to add the whiskermenu to the panel, it doesn't show up in the list of selectable panel items.

[novoid]

I just moved the list of xfce packages including the add-ons/plugins from homemanager/xfce.nix to configuration.nix (NixOS without/outside of Home-Manager) and it worked.

Thanks for that tip from https://graz.social/@soupglasses@hachyderm.io/110828001525165755