Sorry, thats not the complete truth. It also requires: Gtkmm 2.4 and above. LibGlademm 2.4 and above.FlowCanvas
I believe that list was for the engine alone, I suspect(Cant be sure not having used OM myself) that what you are listing is for the GUI, NOT the engine.
The website would seem to confirm this as the list you posted is directly below this... "The Gtk client requires:"
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