Seeks in the stream by the given
offset, modified by
gSeekableSeek(object, offset, type = "G_SEEK_SET", cancellable = NULL, .errwarn = TRUE)
cancellable is not
NULL, then the operation can be cancelled by
triggering the cancellable object from another thread. If the operation
was cancelled, the error
G_IO_ERROR_CANCELLED will be returned.
A list containing the following elements:
TRUEif successful. If an error has occurred, this function will return
errorappropriately if present.
GErrorlocation to store the error occuring, or