add getCommonAncestor() method

src/core/node.js

@@ -290,4 +290,29 @@ var MinderNode = KityMinder.MinderNode = kity.createClass('MinderNode', {
         this.setTmpData(utils.clonePlainObject(node.getTmpData()));
         return this;
     }
-});
\ No newline at end of file
+});
+
+MinderNode.getCommonAncestor = function(nodeA, nodeB) {
+    switch (arguments.length) {
+        case 1:
+            return nodeA;
+
+        case 2:
+            if (nodeA.contains(nodeB)) {
+                return nodeA;
+            }
+            if (nodeB.contains(nodeA)) {
+                return nodeB;
+            }
+            var ancestor = nodeA.parent;
+            while (ancestor && !ancestor.contains(nodeB)) {
+                ancestor = ancestor.parent;
+            }
+            return ancestor;
+
+        default:
+            return Array.prototype.reduce.call(arguments, function(prev, current) {
+                return MinderNode.getCommonAncestor(prev, current);
+            }, nodeA);
+    }
+};
\ No newline at end of file

src/core/utils.js

@@ -172,22 +172,6 @@ var utils = Utils = KityMinder.Utils = {
             if (obj.hasOwnProperty(key)) return false;
         return true;
     },
-    getNodeCommonAncestor: function(nodeA, nodeB) {
-        if (nodeA === nodeB) {
-            return nodeA.parent;
-        }
-        if (nodeA.contains(nodeB)) {
-            return nodeB;
-        }
-        if (nodeB.contains(nodeA)) {
-            return nodeB;
-        }
-        var parent = nodeA.parent;
-        while (!parent.contains(nodeB)) {
-            parent = parent.parent;
-        }
-        return parent;
-    },
     loadFile: function() {
         var tmpList = [];
 

src/module/node.js

@@ -42,7 +42,7 @@ var RemoveNodeCommand = kity.createClass('RemoverNodeCommand', {
     base: Command,
     execute: function(km, text) {
         var nodes = km.getSelectedNodes();
-        var ancestor = km.getSelectedAncestors()[0];
+        var ancestor = MinderNode.getCommonAncestor.apply(null, nodes);
 
         nodes.forEach(function(node) {
             km.removeNode(node);