gxp layertree checkbox click

cb_click

diff --git a/src/script/plugins/LayerTree.js b/src/script/plugins/LayerTree.js
index 7c04c07..b53c701 100644
--- a/src/script/plugins/LayerTree.js
+++ b/src/script/plugins/LayerTree.js
@@ -223,6 +223,12 @@ gxp.plugins.LayerTree = Ext.extend(gxp.plugins.Tool, {
                 }
                 attr.listeners = {
                     rendernode: function(node) {
+                        var cb = node.getUI().checkbox;
+                        if (cb && Ext.get(cb).getAttribute('type') === 'checkbox') {
+                            Ext.get(cb).on('click', function() {
+                                alert('click');
+                            });
+                        }
                         if (record === this.target.selectedLayer) {
                             node.select();
                         }