Merge branch 'master' into jgrpp

# Conflicts:
#	src/core/geometry_type.hpp
#	src/error_gui.cpp
#	src/rail_gui.cpp
#	src/tree_gui.cpp
#	src/vehicle_gui.cpp
#	src/widgets/dropdown.cpp

src/airport_gui.cpp

@@ -392,7 +392,7 @@ public:
 			case WID_AP_AIRPORT_SPRITE:
 				if (this->preview_sprite != 0) {
 					Dimension d = GetSpriteSize(this->preview_sprite);
-					DrawSprite(this->preview_sprite, COMPANY_SPRITE_COLOUR(_local_company), (r.left + r.right - d.width) / 2, (r.top + r.bottom - d.height) / 2);
+					DrawSprite(this->preview_sprite, COMPANY_SPRITE_COLOUR(_local_company), CenterBounds(r.left, r.right, d.width), CenterBounds(r.top, r.bottom, d.height));
 				}
 				break;