Arena 3 calculate button bug

[JonasThiem]

Since apparently noone cared to respond to my bug report submitted to the Arena contact form for weeks, I'll repost it here:

There is an Arena engine stop/start button bug, apparent in Arena 3.0 Build 2542 in wine-1.5.11 on Fedora 17 (and probably on native Windows aswell I assume).

In the "Movelist" tab, there is a "Let the engine calculate" button which, when clicked, turns into a red cross to stop calculating.

When clicking this button fast 6x times, this happens in Arena's engine log:

2012-09-02 16:45:13.311*1*Start calc, move no: 1
2012-09-02 16:45:13.423-->1:stop
2012-09-02 16:45:13.619*1*Start calc, move no: 1
2012-09-02 16:45:13.732-->1:stop
2012-09-02 16:45:13.934*1*Start calc, move no: 1
2012-09-02 16:45:14.052-->1:stop
2012-09-02 16:45:15.142-->1:position startpos moves d2d4
2012-09-02 16:45:15.157-->1:go wtime 300000 btime 300000 winc 0 binc 0
2012-09-02 16:45:15.192-->1:position startpos moves d2d4
2012-09-02 16:45:15.204-->1:go wtime 300000 btime 300000 winc 0 binc 0
2012-09-02 16:45:15.242-->1:position startpos moves d2d4
2012-09-02 16:45:15.253-->1:go wtime 300000 btime 300000 winc 0 binc 0
2

In the end, the engine shouldn't be calculating since I started and stopped calculation 3 times, so I would expect this instead:

position startpos moves d2d4
go wtime 300000 btime 300000 winc 0 binc 0
stop
position startpos moves d2d4
go wtime 300000 btime 300000 winc 0 binc 0
stop
position startpos moves d2d4
go wtime 300000 btime 300000 winc 0 binc 0
stop

Both Arena's engine log and Arena now counting down the thinking time of the engine indicate that Arena messed itself up and is now having the engine calculate a move.

However, the "Let the engine calculate" button does NOT reflect this and is NOT a red cross (as it should be during calculation), but appears as normal gears icon for starting calculation. Obviously, the game clock, engine log disagree with the button on what is happening right now.

For the sake of clean protocol handling and a consistent user interface state, I suggest a fix.