--- a/src/articulated_vehicles.cpp	Mon Apr 21 13:45:03 2008 +0000
+++ b/src/articulated_vehicles.cpp	Mon Apr 21 14:33:33 2008 +0000
@@ -25,7 +25,7 @@
 	uint i;
 	for (i = 1; i < MAX_UVALUE(EngineID); i++) {
 		uint16 callback = GetVehicleCallback(CBID_VEHICLE_ARTIC_ENGINE, i, 0, engine_type, v);
-		if (callback == CALLBACK_FAILED || callback == 0xFF) break;
+		if (callback == CALLBACK_FAILED || GB(callback, 0, 8) == 0xFF) break;
 	}
 
 	delete v;
@@ -52,7 +52,7 @@
 
 	for (uint i = 1; i < MAX_UVALUE(EngineID); i++) {
 		uint16 callback = GetVehicleCallback(CBID_VEHICLE_ARTIC_ENGINE, i, 0, engine, NULL);
-		if (callback == CALLBACK_FAILED || callback == 0xFF) break;
+		if (callback == CALLBACK_FAILED || GB(callback, 0, 8) == 0xFF) break;
 
 		EngineID artic_engine = GetFirstEngineOfType(type) + GB(callback, 0, 7);
 
@@ -78,7 +78,7 @@
 
 	for (uint i = 1; i < MAX_UVALUE(EngineID); i++) {
 		uint16 callback = GetVehicleCallback(CBID_VEHICLE_ARTIC_ENGINE, i, 0, v->engine_type, v);
-		if (callback == CALLBACK_FAILED || callback == 0xFF) return;
+		if (callback == CALLBACK_FAILED || GB(callback, 0, 8) == 0xFF) return;
 
 		/* Attempt to use pre-allocated vehicles until they run out. This can happen
 		 * if the callback returns different values depending on the cargo type. */

--- a/src/economy.cpp	Mon Apr 21 13:45:03 2008 +0000
+++ b/src/economy.cpp	Mon Apr 21 14:33:33 2008 +0000
@@ -1595,7 +1595,7 @@
 		byte load_amount = EngInfo(v->engine_type)->load_amount;
 		if (_patches.gradual_loading && HasBit(EngInfo(v->engine_type)->callbackmask, CBM_VEHICLE_LOAD_AMOUNT)) {
 			uint16 cb_load_amount = GetVehicleCallback(CBID_VEHICLE_LOAD_AMOUNT, 0, 0, v->engine_type, v);
-			if (cb_load_amount != CALLBACK_FAILED && cb_load_amount != 0) load_amount = cb_load_amount & 0xFF;
+			if (cb_load_amount != CALLBACK_FAILED && GB(cb_load_amount, 0, 8) != 0) load_amount = GB(cb_load_amount, 0, 8);
 		}
 
 		GoodsEntry *ge = &st->goods[v->cargo_type];

--- a/src/newgrf_generic.cpp	Mon Apr 21 13:45:03 2008 +0000
+++ b/src/newgrf_generic.cpp	Mon Apr 21 14:33:33 2008 +0000
@@ -176,5 +176,7 @@
 	object.u.generic.count             = count;
 	object.u.generic.station_size      = station_size;
 
-	return GetGenericCallbackResult(feature, &object, file);
+	uint16 callback = GetGenericCallbackResult(feature, &object, file);
+	if (callback != CALLBACK_FAILED) callback = GB(callback, 0, 8);
+	return callback;
 }

--- a/src/newgrf_house.cpp	Mon Apr 21 13:45:03 2008 +0000
+++ b/src/newgrf_house.cpp	Mon Apr 21 14:33:33 2008 +0000
@@ -527,7 +527,7 @@
 	/* Check callback 21, which determines if a house should be destroyed. */
 	if (HasBit(hs->callback_mask, CBM_HOUSE_DESTRUCTION)) {
 		uint16 callback_res = GetHouseCallback(CBID_HOUSE_DESTRUCTION, 0, 0, GetHouseType(tile), GetTownByTile(tile), tile);
-		if (callback_res != CALLBACK_FAILED && callback_res > 0) {
+		if (callback_res != CALLBACK_FAILED && GB(callback_res, 0, 8) > 0) {
 			ClearTownHouse(GetTownByTile(tile), tile);
 			return false;
 		}

--- a/src/newgrf_spritegroup.cpp	Mon Apr 21 13:45:03 2008 +0000
+++ b/src/newgrf_spritegroup.cpp	Mon Apr 21 14:33:33 2008 +0000
@@ -80,37 +80,6 @@
 TemporaryStorageArray<uint32, 0x110> _temp_store;
 
 
-static inline bool Is8BitCallback(const ResolverObject *object)
-{
-	/* Var 0x7E procedure results are always 15 bit */
-	if (object == NULL || object->procedure_call) return false;
-
-	switch (object->callback) {
-		/* All these functions are 15 bit callbacks */
-		case CBID_STATION_SPRITE_LAYOUT:
-		case CBID_VEHICLE_REFIT_CAPACITY:
-		case CBID_HOUSE_COLOUR:
-		case CBID_HOUSE_CARGO_ACCEPTANCE:
-		case CBID_INDUSTRY_LOCATION:
-		case CBID_HOUSE_ACCEPT_CARGO:
-		case CBID_INDTILE_CARGO_ACCEPTANCE:
-		case CBID_INDTILE_ACCEPT_CARGO:
-		case CBID_VEHICLE_COLOUR_MAPPING:
-		case CBID_HOUSE_PRODUCE_CARGO:
-		case CBID_INDTILE_SHAPE_CHECK:
-		case CBID_VEHICLE_SOUND_EFFECT:
-		case CBID_VEHICLE_MODIFY_PROPERTY: // depends on queried property
-		case CBID_CARGO_PROFIT_CALC:
-		case CBID_SOUNDS_AMBIENT_EFFECT:
-		case CBID_CARGO_STATION_RATING_CALC:
-			return false;
-
-		/* The rest is a 8 bit callback, which should be truncated properly */
-		default:
-			return true;
-	}
-}
-
 static inline uint32 GetVariable(const ResolverObject *object, byte variable, byte parameter, bool *available)
 {
 	/* First handle variables common with Action7/9/D */
@@ -236,7 +205,7 @@
 	if (group->g.determ.num_ranges == 0) {
 		/* nvar == 0 is a special case -- we turn our value into a callback result */
 		nvarzero.type = SGT_CALLBACK;
-		nvarzero.g.callback.result = GB(value, 0, Is8BitCallback(object) ? 8 : 15);
+		nvarzero.g.callback.result = value;
 		return &nvarzero;
 	}
 
@@ -295,14 +264,6 @@
 		case SGT_REAL:          return object->ResolveReal(object, group);
 		case SGT_DETERMINISTIC: return ResolveVariable(group, object);
 		case SGT_RANDOMIZED:    return ResolveRandom(group, object);
-		case SGT_CALLBACK: {
-			if (!Is8BitCallback(object)) return group;
-
-			static SpriteGroup result8bit;
-			result8bit.type = SGT_CALLBACK;
-			result8bit.g.callback.result = GB(group->g.callback.result, 0, 8);
-			return &result8bit;
-		}
 		default:                return group;
 	}
 }

--- a/src/rail_gui.cpp	Mon Apr 21 13:45:03 2008 +0000
+++ b/src/rail_gui.cpp	Mon Apr 21 14:33:33 2008 +0000
@@ -952,7 +952,7 @@
 				const StationSpec *statspec = GetCustomStationSpec(_railstation.station_class, i);
 
 				if (statspec != NULL && statspec->name != 0) {
-					if (HasBit(statspec->callbackmask, CBM_STATION_AVAIL) && GetStationCallback(CBID_STATION_AVAILABILITY, 0, 0, statspec, NULL, INVALID_TILE) == 0) {
+					if (HasBit(statspec->callbackmask, CBM_STATION_AVAIL) && GB(GetStationCallback(CBID_STATION_AVAILABILITY, 0, 0, statspec, NULL, INVALID_TILE), 0, 8) == 0) {
 						GfxFillRect(8, y - 2, 127, y + 10, (1 << PALETTE_MODIFIER_GREYOUT));
 					}
 
@@ -1097,7 +1097,7 @@
 			statspec = GetCustomStationSpec(_railstation.station_class, y);
 			if (statspec != NULL &&
 				HasBit(statspec->callbackmask, CBM_STATION_AVAIL) &&
-				GetStationCallback(CBID_STATION_AVAILABILITY, 0, 0, statspec, NULL, INVALID_TILE) == 0) return;
+				GB(GetStationCallback(CBID_STATION_AVAILABILITY, 0, 0, statspec, NULL, INVALID_TILE), 0, 8) == 0) return;
 
 			_railstation.station_type = y;
 
@@ -1510,7 +1510,7 @@
 
 				if (statspec != NULL &&
 						HasBit(statspec->callbackmask, CBM_STATION_AVAIL) &&
-						GetStationCallback(CBID_STATION_AVAILABILITY, 0, 0, statspec, NULL, INVALID_TILE) == 0) {
+						GB(GetStationCallback(CBID_STATION_AVAILABILITY, 0, 0, statspec, NULL, INVALID_TILE), 0, 8) == 0) {
 					GfxFillRect(4 + i * 68, 18, 67 + i * 68, 75, (1 << PALETTE_MODIFIER_GREYOUT));
 				}
 			}
@@ -1530,7 +1530,7 @@
 				const StationSpec *statspec = GetCustomStationSpec(STAT_CLASS_WAYP, type);
 				if (statspec != NULL &&
 						HasBit(statspec->callbackmask, CBM_STATION_AVAIL) &&
-						GetStationCallback(CBID_STATION_AVAILABILITY, 0, 0, statspec, NULL, INVALID_TILE) == 0) return;
+						GB(GetStationCallback(CBID_STATION_AVAILABILITY, 0, 0, statspec, NULL, INVALID_TILE), 0, 8) == 0) return;
 
 				_cur_waypoint_type = type;
 				SndPlayFx(SND_15_BEEP);

--- a/src/station_cmd.cpp	Mon Apr 21 13:45:03 2008 +0000
+++ b/src/station_cmd.cpp	Mon Apr 21 14:33:33 2008 +0000
@@ -1014,7 +1014,7 @@
 		}
 
 		/* Check if the station is buildable */
-		if (HasBit(statspec->callbackmask, CBM_STATION_AVAIL) && GetStationCallback(CBID_STATION_AVAILABILITY, 0, 0, statspec, NULL, INVALID_TILE) == 0) {
+		if (HasBit(statspec->callbackmask, CBM_STATION_AVAIL) && GB(GetStationCallback(CBID_STATION_AVAILABILITY, 0, 0, statspec, NULL, INVALID_TILE), 0, 8) == 0) {
 			return CMD_ERROR;
 		}
 	}

--- a/src/town_cmd.cpp	Mon Apr 21 13:45:03 2008 +0000
+++ b/src/town_cmd.cpp	Mon Apr 21 14:33:33 2008 +0000
@@ -1936,7 +1936,7 @@
 
 			if (HasBit(hs->callback_mask, CBM_HOUSE_ALLOW_CONSTRUCTION)) {
 				uint16 callback_res = GetHouseCallback(CBID_HOUSE_ALLOW_CONSTRUCTION, 0, 0, house, t, tile);
-				if (callback_res != CALLBACK_FAILED && callback_res == 0) continue;
+				if (callback_res != CALLBACK_FAILED && GB(callback_res, 0, 8) == 0) continue;
 			}
 		}
 

--- a/src/train_cmd.cpp	Mon Apr 21 13:45:03 2008 +0000
+++ b/src/train_cmd.cpp	Mon Apr 21 14:33:33 2008 +0000
@@ -240,7 +240,7 @@
 			if (HasBit(EngInfo(u->engine_type)->callbackmask, CBM_TRAIN_WAGON_POWER)) {
 				uint16 callback = GetVehicleCallback(CBID_TRAIN_WAGON_POWER, 0, 0, u->engine_type, u);
 
-				if (callback != CALLBACK_FAILED) u->u.rail.cached_vis_effect = callback;
+				if (callback != CALLBACK_FAILED) u->u.rail.cached_vis_effect = GB(callback, 0, 8);
 			}
 
 			if (rvi_v->pow_wag_power != 0 && rvi_u->railveh_type == RAILVEH_WAGON &&