Uncaught TypeError: Cannot read property 'position' of null

[pawelstep]

Hi,
when clicking frequently on core-dropdown with paper elements, a null error appears on console.
I guess this is because rendering of paper elements takes a while with its fancy animations, but a new click in the dropdown causes that to happen. The sample code attached below - tried in Chrome "Version 38.0.2125.111 m", on PC/Win7. It is enough to make a series of quick double-clicks on dropdown to get an error msg in console.

Would some kind of check for null or action deferral be needed?

Best regards,
PawelS.

<polymer-element name="login-info" attributes="loggedin user" noscript>
    <template>
            <template if='{{loggedin}}'>
                <paper-menu-button>
                    <paper-item>
                        <span class="puser">User: {{user}}</span>
                    </paper-item>
                    <paper-dropdown class="dropdown">
                        <paper-item>
                            <span class="puser">User: {{user}}</span>
                        </paper-item>
                        <paper-item on-click="{{buttonOnLogout}}">LogOut</paper-item>
                    </paper-dropdown>
                </paper-menu-button>
            </template>
    </template>
</polymer-element>

[pawelstep]

That's the error image.

[Ortham]

I also get the same error: it's present in core-dropdown.html on line 186 in Polymer 0.5.1.

From what I can tell, the error is Cannot read property 'position' of null if you open one menu quickly after another, but I can also get a Cannot read property 'position' of undefined on the same line.

I'm not sure what the case for the latter happening is, but I'm opening <paper-dropdown> menus in <core-list> items, where the items can reset the dropdown state, so maybe that's happening because the <core-dropdown> code doesn't realise the open menus have been closed via Javascript, or vice versa?

Edit: PR #14 fixes this for me.