AddCount := 1;
    I := PosEx(';',Exts,1);
    while I > 0 do
    begin
      P := I;
      if (WMPCount+AddCount) = WMPOpenMaxExt then break;
      Inc(AddCount);
      I := PosEx(';',Exts,P);
    end;
    if I > 0 then Delete(Exts,P,Length(Exts) - P + 1);