What does the apply button do?

[MarkShot]

When I don't click it, it appears that my changes are saved to the current config.

When I do click it, it appears that if create a new game with some other options, everything resets to the defaults the next time I used GRF.

I have no idea what this does.

Thanks.

PS: I would prefer my changes would persist once clicked. So, I would not need to reconfigure each time I use something different.

[acs121]

Basically its more common use is in a command you'd have to type in the console : set newgrf_developer_tools 1.
This command literally allows for adding and removing NewGRFs from a game, although it's not this safe and you should also take safety measures while adding/removing.

[+] Spoiler

Adding NewGRFs generally isn't a problem. You could tell me that if one used the default vehicles and added another set of vehicles, the default vehicles are going to bug. Well... no. Default vehicles are still into the game whatever you do to them.

If you remove any vehicle NewGRF, well, it can cause a few problems, and even if you'd still want to do it, I'd suggest you remove all vehicles of this set from your fleet.

If you remove any town name NewGRF, town names will be the random, original, English ones.

If you remove any NewGRF that is only altering graphics, you shouldn't have problems with it.

Oh, and never ever remove an industry NewGRF. It can turn out horribly bad.

[eekee]

PS: I would prefer my changes would persist once clicked. So, I would not need to reconfigure each time I use something different.

If this means what I think it does, I just filed a feature request. Been meaning to for a while.