Open combobox

When my user focus my combobox can I automatic open the popup? even without typing something

There’s no existing server-side API for that. It might be possible with a custom client-side Extension; the suggestionPopup member variable of VComboBox is publicly visible and you could perhaps call the public showSuggestions method. No guarantees that it will work in all cases, though, ComboBox’s client side is notoriously tricky.

-Olli

This feature ( openPopup() and openPopup(int page) methods ) is included in [PrefixComboBox add-on]
(https://vaadin.com/directory/component/prefixcombobox) for Vaadin 8, which an extended ComboBox, a collection of missing features.