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.
a 'BidiString' holds both the logical content and the visual reordered
version of the content of a string. this helps to reduce the number of
calls to reorder the string before drawing it (as introduced in the patch
from Ken Bloom) and to be more consistent in menus and textboxes (drawing
cursors and underlining text).
