+ int old_element = Feld[x][y];
+ unsigned int new_bitmask = (dx + 1) << (dy * 2);
+
+ if (IS_MM_WALL_EDITOR(element))
+ {
+ element = map_mm_wall_element_editor(element) | new_bitmask;
+
+ if (IS_MM_WALL(old_element))
+ element |= MM_WALL_BITS(old_element);
+ }
+ else if (IS_MM_WALL(old_element) && element == EL_EMPTY)
+ {
+ int element_changed = old_element & ~new_bitmask;
+
+ if (MM_WALL_BITS(element_changed) != 0)
+ element = element_changed;
+ }