Issues with VaadinDatePicker inside of an IronCollapse

[nikwenk]

Hi,

there are some issues with VaadinDatePicker inside of an IronCollapse. You can not select a date when the DatePicker is opened. It looks like the focus is lost. If you click on the "today" button the focus seems to be back and everything works fine.

Example:

<p:PaperMaterial ui:field="btHeader" elevation="0" addStyleNames="{style.header}"><paper-ripple></paper-ripple></p:PaperMaterial>
     <i:IronCollapse ui:field="collapse">
          <g:HTMLPanel ui:field="contentPanel" addStyleNames="{style.content}">
               <v:VaadinDatePicker label="Test"/>
          </g:HTMLPanel> 
     </i:IronCollapse>

thanks