I'd like to suggest that the [tag:top-bar] tag be done away with. I propose the following criteria:

 - if the "thing" can be used by itself, or customised by itself, it might make sense to refer to it with tag - in which case we tag it with a suitable name, like [tag:mate-panel], [tag:budgie-panel], [tag:xfce4-panel]\*, [tag:lxpanel] (which are the names of the respective software, afaict), or, alternatively, with [tag:panel] + [tag:name-of-DE].
 - if the "thing" is an inflexible component of something else, which can't be customised or used on its own, but only via the larger something else, then we should tag it with that something else - [tag:gnome-shell], [tag:cinnamon]...

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\* it seems the XFCE4 Panel is called [tag:xfce-panel], even though neither the package nor the command uses this name.