--- a/src/newgrf_house.cpp	Fri Aug 03 19:16:36 2007 +0000
+++ b/src/newgrf_house.cpp	Fri Aug 03 22:09:42 2007 +0000
@@ -274,7 +274,7 @@
 	res->u.house.town     = town;
 	res->u.house.house_id = house_id;
 
-	res->callback        = 0;
+	res->callback        = CBID_NO_CALLBACK;
 	res->callback_param1 = 0;
 	res->callback_param2 = 0;
 	res->last_value      = 0;
@@ -282,7 +282,7 @@
 	res->reseed          = 0;
 }
 
-uint16 GetHouseCallback(uint16 callback, uint32 param1, uint32 param2, HouseID house_id, Town *town, TileIndex tile)
+uint16 GetHouseCallback(CallbackID callback, uint32 param1, uint32 param2, HouseID house_id, Town *town, TileIndex tile)
 {
 	ResolverObject object;
 	const SpriteGroup *group;
@@ -314,10 +314,7 @@
 		image = dtss->image + stage;
 		pal   = dtss->pal;
 
-		if (!HASBIT(image, SPRITE_MODIFIER_OPAQUE) && HASBIT(_transparent_opt, TO_HOUSES)) {
-			SETBIT(image, PALETTE_MODIFIER_TRANSPARENT);
-			pal = PALETTE_TO_TRANSPARENT;
-		} else if (HASBIT(image, PALETTE_MODIFIER_COLOR)) {
+		if ((HASBIT(image, SPRITE_MODIFIER_OPAQUE) || !HASBIT(_transparent_opt, TO_HOUSES)) && HASBIT(image, PALETTE_MODIFIER_COLOR)) {
 			if (pal == 0) {
 				const HouseSpec *hs = GetHouseSpecs(house_id);
 				if (HASBIT(hs->callback_mask, CBM_BUILDING_COLOUR)) {
@@ -339,7 +336,8 @@
 				image, pal,
 				ti->x + dtss->delta_x, ti->y + dtss->delta_y,
 				dtss->size_x, dtss->size_y,
-				dtss->size_z, ti->z + dtss->delta_z
+				dtss->size_z, ti->z + dtss->delta_z,
+				HASBIT(_transparent_opt, TO_HOUSES)
 			);
 		} else {
 			AddChildSpriteScreen(image, pal, dtss->delta_x, dtss->delta_y);
@@ -353,7 +351,7 @@
 	const SpriteGroup *group;
 	ResolverObject object;
 
-	if (ti->tileh != SLOPE_FLAT) DrawFoundation(ti, ti->tileh);
+	if (ti->tileh != SLOPE_FLAT) DrawFoundation(ti, FOUNDATION_LEVELED);
 
 	NewHouseResolver(&object, house_id, ti->tile, GetTownByTile(ti->tile));