Re: [Bug-XBoard] [bug #8847] Moving backward while examining on FICS not reported to engine

[h.g. muller]

Beware that I hardly ever use an ICS, and that I never used examine mode 
before.
But I tried it for the occasion, and it seems the ICS has commands 
"forward" and
"backward" that can be used to step through the game (possibly in steps of 
multiple
moves). After each such command it sends a new board.

I would have expected that new board, if it has a sequence number equal to the
current board + 1, to be sent to the engine as a move, and if not, (because 
I enter
"forward 999" or something like that) as a setboard. But perhaps if the 
sequence
number is higher, XBoard would obtain a move list through a "moves" command,
and then load the move list to obtain the position. (I guess this is 
preferable, as
it would make the engine aware of the game history, which can be important for
detecting rep-draws.)

So now on "backward", when the sequence number of the new board is lower,
both strategies should still work. (Which made me wonder what to fix.) If 
XBoard
sends a setboard it should not matter if you moved forward or backward, and if
it requests a move list (or perhaps already is in posession of the move 
list) it
can reload the game into the engine. There is no need to recognize the special
case of backing up a single move, and using "undo" on the engine. (Which many
engines do not implement anyway.)

It would be easy enough to put code in BackwardEvent() that detects if the 
engine
is analyzing an ICS game, and send "undo" to it in that case.

Problem is that I don't seem to be able to even get into the situation 
where this
issue would manifest itself. When I log onto FICS in zippy mode with Fruit, 
start
examining a stored game, and try to switch on analysis mode, I get the error
message from WinBoard: "you are not observing a game". I tried to observe
a game that was in progress, start analysis mode, and then give the "examine"
command, but then it did not give me a game I could step through, and when I
typed "unobserve" to try to examine, the engine stopped analysing.

SO what combination of XBoard / ICS commands I have to give to test this???