looking further and the hidden window isn't added to the list gen_ff has of embedded windows (which is understandable but isn't too helpful in this scenario) and it's due to that which is leading to the failure i mentioned above with it then being able to create the frame. so i think once i've worked out what and where the list of embedded is generated from in gen_ff (as the api in winamp.exe which provides the known list is providing the correct number of windows so it's down to the gen_ff handling it seems).
did i mention i hate modern skins? if not then please note this for the future
-daz