I'm looking for an "icon manager" functionality for the
openbox (or similar) x11 window manager.

For those who may not be familar with this possibly archaic
concept, icon managers (as in twm) is a set of of "boxes"
that contains lists of the iconized windows.

A windowd is assigned to a specific specfic icon mamager
according to the WM_CLASS property of the wndow, and will
display the WM_ICON_NAME to distinguish from other icons.

For example,

WM_ICON_NAME(STRING) = "myxterm@mymachine"
WM_CLASS(STRING) = "xterm", "XTerm"

Does anyone know about such a widget for openbox?