Overrides the Seek method.
Source position: classesh.inc line 1479
| public function THandleStream.Seek( | 
| const Offset: Int64; | 
| Origin: TSeekOrigin | 
| ):Int64; override; | 
seek uses the FileSeek method to position the stream on the desired position. Note that handle stream descendants (notably pipes) can override the method to prevent the seek.