//walls on non-cuboid regions no longer introduces gaps in walls beyond 45 degrees (aka slanted roofs :)).

This is a better way to solve #273.

src/main/java/com/sk89q/worldedit/EditSession.java

@@ -1654,7 +1654,20 @@ public class EditSession {
      * @throws MaxChangedBlocksException
      */
     public int makeWalls(final Region region, Pattern pattern) throws MaxChangedBlocksException {
-        return new RegionShape(region).generate(this, pattern, true, true);
+        final int minY = region.getMinimumPoint().getBlockY();
+        final int maxY = region.getMaximumPoint().getBlockY();
+        final ArbitraryShape shape = new RegionShape(region) {
+            @Override
+            protected BaseBlock getMaterial(int x, int y, int z, BaseBlock defaultMaterial) {
+                if (y > maxY || y < minY) {
+                    // Put holes into the floor and ceiling by telling ArbitraryShape that the shape goes on outside the region
+                    return defaultMaterial;
+                }
+
+                return super.getMaterial(x, y, z, defaultMaterial);
+            }
+        };
+        return shape.generate(this, pattern, true);
     }
 
     /**

src/main/java/com/sk89q/worldedit/shape/ArbitraryShape.java

@@ -148,20 +148,6 @@ public abstract class ArbitraryShape {
      * @throws MaxChangedBlocksException
      */
     public int generate(EditSession editSession, Pattern pattern, boolean hollow) throws MaxChangedBlocksException {
-        return generate(editSession, pattern, hollow, false);
-    }
-
-    /**
-     * Generates the shape.
-     *
-     * @param editSession The EditSession to use.
-     * @param pattern The pattern to generate default materials from.
-     * @param hollow Specifies whether to generate a hollow shape.
-     * @param flat If hollow mode is enabled, disregard blocks above/below
-     * @return number of affected blocks.
-     * @throws MaxChangedBlocksException
-     */
-    public int generate(EditSession editSession, Pattern pattern, boolean hollow, boolean flat) throws MaxChangedBlocksException {
         int affected = 0;
 
         for (BlockVector position : getExtent()) {
@@ -201,11 +187,6 @@ public abstract class ArbitraryShape {
                     draw = true;
                     break;
                 }
-
-                if (flat) {
-                    break;
-                }
-
                 if (!isInsideCached(x, y + 1, z, pattern)) {
                     draw = true;
                     break;