Dropdown menu alwways opened - html

Question

I'm learning Polymer and I encountered a little problem while doing the menu. Apparently, when I add the dropdown menu it displays opened always, it doesn't close and open at will. Also, I checked the code at the github repo from Polymer and its demos and can't find out what am I doing wrong.
<paper-toolbar>
<paper-menu-button>
<paper-icon-button icon="menu" class="dropdown-trigger"></paper-icon-button>
<paper-menu class="dropdown-content">
<paper-item>Share</paper-item>
<paper-item>Settings</paper-item>
<paper-item>Help</paper-item>
</paper-menu>
<paper-menu-button>
</paper-menu-button>
<div class="title">Title</div>
<paper-icon-button icon="refresh"></paper-icon-button>
</paper-toolbar>

Answer 1

You are having an extra <paper-menu-button> before
</paper-menu-button>
<div class="title">Title</div>
This is how your code should looks
<base href="http://polygit.org/polymer+:master/components/">
<script src="webcomponentsjs/webcomponents-lite.min.js"></script>
<link href="polymer/polymer.html" rel="import">
<link href="paper-input/paper-input.html" rel="import">
<link href="paper-slider/paper-slider.html" rel="import">
<link href="paper-toolbar/paper-toolbar.html" rel="import">
<link href="paper-menu/paper-menu.html" rel="import">
<link href="paper-menu-button/paper-menu-button.html" rel="import">
<link href="paper-item/paper-item.html" rel="import">
<link href="paper-icon-button/paper-icon-button.html" rel="import">
<link rel="import" href="iron-icons/iron-icons.html">
<dom-module id="my-app">
<template>
<paper-toolbar>
<paper-menu-button>
<paper-icon-button icon="menu" class="dropdown-trigger">+</paper-icon-button>
<paper-menu class="dropdown-content">
<paper-item>Share</paper-item>
<paper-item>Settings</paper-item>
<paper-item>Help</paper-item>
</paper-menu>
</paper-menu-button>
<div class="title">Title</div>
<paper-icon-button icon="refresh"></paper-icon-button>
</paper-toolbar>
</template>
<script>
addEventListener('WebComponentsReady', function() {
Polymer({
is: 'my-app',
properties: {
}
});
});
</script>
</dom-module>
<my-app></my-app>
I don't know if you have imported all the required imports, but here is a Plunkr , you can see it in action