these two allow 'tagging' of arbitrary windows with 'tags' (or 'labels'). such 'tagged' windows can then be used in ':NextWindow (@PROP=foo)' commands to quickly cycle through a subset of available windows.
since the 'tags' are applied as real xproperties to a window they survive a restart of fluxbox or even another windowmanager. the user can also set the tags by using xprop(1).
the next step regarding the UI should be to visualize the tags of a window.
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