an offset, in bytes, which is added to the position specified by type
the position in the file, which can be G_SEEK_CUR (the current position), G_SEEK_SET (the start of the file), or G_SEEK_END (the end of the file)
G_IO_ERROR_NONE if the operation was successful.
Warning g_io_channel_seek has been deprecated since version 2.2 and should not be used in newly-written code. Use g_io_channel_seek_position() instead. Sets the current position in the GIOChannel, similar to the standard library function fseek().