VFP 9 can write large prg files.
Now, because, at the same time, i cannot open two or more program.prg edit windows,
i try this:
open the program.bak in read mode, and edit program.prg.
One ugly surprise:
when i save (only save!!!) VFP says to me:
- File access is denied (Error 1705)
and
- close the edit window, losing all my modifications !!

To use VFP within a Dev Team ?
Example:

- Dev1 open a .prg
- Dev2 cannot open .prg
-   then Dev2 open the .bak
- Dev1 works for 2 hours
- Dev1 a coffee wants drink,
   then it press Save
- Dev1 the coffee does not drink more,
   but one is drunk camomile!

An optimal way in order to pass the days!

Ask: why VFP open a prg in pessimistic lock mode ?
Expected:

- Open a .prg
- At first edit operation:
a) refresh the file with a write lock access

b) when save, if a error occurs, NOT CLOSE THE MODIFY WINDOW !!!!!!!!!

Another point:
the situation is still worse than how much it seems.
If you uses:

MODIFY COMMAND SOMEPROGRAM.BAK NOEDIT && Read only mode

VFP open SOMEPROGRAM.BAK with a write exclusive access !,
and you still must to drink camomile.

Fabio