GUI: "New save" button still enabled when all save locations are used

[karisal]

As a disclaimer this bug report is based on a memory of debugging the Cine engine's savegame handling. AFAIK the bug I encountered seemed to be in the ScummVM's general savegame handling UI code, not in the Cine engine's. That's why I made this bug report from #11625 ("CINE: OS: Game doesn't support more than 20 savegames (and conveys that information very poorly)"). So the following description is an extrapolation based on the debugging, I have NOT tried any other engine than the Cine engine in relation to this bug.

Just try any engine in ScummVM, make the maximum number of savegames supported by an engine and then open the ScummVM's own savegame handling UI in order to try to create a new savegame. The "New save"-button will never be grayed out as it should be when there are the maximum number of savegames already present.

Maybe for testing purposes it may be easy to modify the code of some engine to limit the maximum number of savegames it supports. Or using command line magic to duplicate savegames.

[tag2015]

I looked a bit into this bug. It should be noted that:

• This issue could only happen when using the "grid" save screen, when using the "list" there's no way to go beyond the maximum (as there's no "new save" button),
• Most engines now have a limit of 100 or even 1000 saves, so the probability of filling all savestates is quite slim,
• Two engines that have a low maxsaves number are Teenagent and Twine. In both cases, if all the saves are used, the button is properly grayed out. The only problem I noted happens if you go to the list view and then back again to the grid view. In this case the button won't get disabled (but still you can't save, if you try it will simply go back to the game without asking to name the file)

All things considered, this is a really borderline case, so setting to low priority (but I'll see if I can solve the last issue)