Enable easy way to reset scroll position when changing UI

[samie]

Many times when building UI with Flow component that changes the UI a lot, I want to reset the scroll to the top to simulate the page change instead of keeping the current position.

Example case:

        showAll = new Div();
        showAll.setClassName(CLASS_NAME + "__all");
        showAll.setText("show all...");
        showAll.addClickListener(e -> {
            UI.getCurrent().getPage().executeJavaScript("document.body.parentElement.scrollTop = 0;");
            /* ... update the UI... */  
        });

This is event more typical when using view navigation at the same time, like:

            UI.getCurrent().navigateTo("/");

This is so typical case that should be handled on the UI level method.

[mshabarov]

@samie this can be achieved in the latest version of Flow by calling Component:: scrollIntoView(). Do you think we still need this ticket?