先设置好父亲的一些布局属性

src/layout/btree.js

@@ -79,10 +79,6 @@ layouts.forEach(function(name) {
 
         doLayout: function(parent, children) {
 
-            if (!children.length) {
-                return false;
-            }
-
             var pbox = parent.getContentBox();
 
             if (axis == 'x') {
@@ -93,6 +89,10 @@ layouts.forEach(function(name) {
                 parent.setLayoutVectorOut(new kity.Vector(0, dir));
             }
 
+            if (!children.length) {
+                return false;
+            }
+
             children.forEach(function(child) {
                 var cbox = child.getContentBox();
                 child.setLayoutTransform(new kity.Matrix());