def OpStroffEx(ea, n, strid, delta):
    path = idaapi.tid_array(1)
    path[0] = strid
    return idaapi.op_stroff(ea, n, path.cast(), 1, delta)
Convert operand to an offset in a structure
dataset/ETHPy150Open EiNSTeiN-/idapython/python/idc.py/OpStroffEx