(svn r21694) -Fix: changing AI settings ingame was impossible when the difficulty level was other than custom

src/settings.cpp

@@ -977,6 +977,9 @@ static void ValidateSettings()
 
 static bool DifficultyReset(int32 level)
 {
+	/* In game / in the scenario editor you can set the difficulty level only to custom. This is
+	 * needed by the AI Gui code that sets the difficulty level when you change any AI settings. */
+	if (_game_mode != GM_MENU && level != 3) return false;
 	SetDifficultyLevel(level, (_game_mode == GM_MENU) ? &_settings_newgame.difficulty : &_settings_game.difficulty);
 	return true;
 }

src/table/settings.h

@@ -362,7 +362,7 @@ const SettingDesc _settings[] = {
 	 SDT_CONDVAR(GameSettings, difficulty.line_reverse_mode,         SLE_UINT8, 97, SL_MAX_VERSION, 0, 0,     0,     0,      1,  1, STR_REVERSE_AT_END_OF_LINE_AND_AT_STATIONS,DifficultyChange),
 	 SDT_CONDVAR(GameSettings, difficulty.disasters,                 SLE_UINT8, 97, SL_MAX_VERSION, 0, 0,     0,     0,      1,  1, STR_DISASTERS_OFF,                         DifficultyChange),
 	 SDT_CONDVAR(GameSettings, difficulty.town_council_tolerance,    SLE_UINT8, 97, SL_MAX_VERSION, 0, 0,     0,     0,      2,  1, STR_CITY_APPROVAL_PERMISSIVE,                            DifficultyNoiseChange),
-	 SDT_CONDVAR(GameSettings, difficulty.diff_level,                SLE_UINT8, 97, SL_MAX_VERSION, 0,NG,     3,     0,      3,  0, STR_NULL,                                  DifficultyReset),
+	 SDT_CONDVAR(GameSettings, difficulty.diff_level,                SLE_UINT8, 97, SL_MAX_VERSION, 0, 0,     3,     0,      3,  0, STR_NULL,                                  DifficultyReset),
 
 	/* There are only 21 predefined town_name values (0-20), but you can have more with newgrf action F so allow these bigger values (21-255). Invalid values will fallback to english on use and (undefined string) in GUI. */
  SDT_CONDOMANY(GameSettings, game_creation.town_name,              SLE_UINT8, 97, SL_MAX_VERSION, 0,NN, 0, 255, _town_names,      STR_NULL,                                  NULL, NULL),