When loading components in Vaadin, during the loading process, it displays the progressbar before any component can be seen visually. Let's say you need to add items and and a speciific item needs to have been selected (visually) after the MainLayout and other components are loaded (after the progressbar at the top stops).
Example, AppLayout contains header divs and other buttons but there is a combobox that you would like to populate and select an item from at the same time, say list of country where user has visited. When the data is fetched from db, there is an extra filter for the list before the filtered items are set into the combobox, this filter will select a single item that will set as the item to display.
All of this when loading will just show the progressbar instead of showing the header and other buttons.
I have tried onAttach, afterNavigation, etc. but all such events don't work and the progressbar always displays (on the top of the page) and nothing else can be seen visually.