You have two options:
1. Use FileReadByte in a loop until the error flag is set (will read the byte as an integer so you need to use IntFmt to convert it to a character).
2. Use
ReadFile API via the System plug-in. The handle returned from FileOpen should work.
In both cases, you are limited to 1024 characters (or 8129 for the
special build) so reading the entire contents of the file is not a good idea.
Also why do a FileSeek? When you open a file, the pointer will be at the beginning of the file anyway.
Stu