You could set the tabindex property to -1, but this would remove the widget from the tabindex entirely
You could also place another widget as the first item in the dataview (e.g. the HTMLsnippet), but this would introduce possible unwanted changes to the layout of the page.
I think the issue is not necessarily that the focus is set to the textarea/dropdown, but that it selects all of the text in the textarea or the selected dropdown value. If the user is not careful the existing value might be cleared or changed.