I have a large project on Vaadin, it works fine on Vaadin 7. But i have start to upgrade it to 8.0 and then to 8.1 versions. Everything is fine but focusing on ComboBoxes inside Grid. It sometimes works, but sometimes not. I look at debug console online and see that there is command to set focus received. But it not always really set focus on right component. On Chrome focus can lost from all components, in Firefox focus stays on previously focused component.
I have created simple testing Servlet with Grid component, which has some ComboBoxes as columns. It must imitate problem from large project's Servlet. On each ComboBox added valueChangeListener, which moves focus to next ComboBox. At the last ComboBox there is moving focus on next line first ComboBox. And so on, until to last line, where it move focus on first line first ComboBox.
In test Servlet i cannot find error, all works like i want. Almost two weeks i tried to solve my problem, but cannot.
Update 2017-10-18: I think i found my problem. There is an focus lost occured if line with focused component moves to another position. I attach simple example. It is an Vaadin Servlet with 2-columns Grid. For focus testing i added static trigger with button. Open servlet in two browsers, select some values in ComboBoxes and play with buttons. On press button in first page it must react on second page and mix two lines. Periodically check focus on second page. On some button press line with focused ComboBox will move to another place and lost focus.