Hi
It's very easy. In your .xml file add the boundary panel and the widget container
<g:AbsolutePanel ui:field="boundaryPanel" addStyleNames="mt10 mb10">
<g:ScrollPanel addStyleNames="{style.scrollPanel}">
<g:VerticalPanel ui:field="containerPanel" spacing="2"/>
</g:ScrollPanel>
</g:AbsolutePanel>
Then, in your view create the drag controller, the handler, the container and the drop controller, as shown in the examples.
You can initialize them in your view's constructor or defer it's creation to another method called from your presenter if you need to access the UiHandlers.
Regards.