Vaadin Framework 8.4.0 is a feature release version

Enhancements in Vaadin Framework 8.4

ComboBox has a better handling of new items with NewItemProvider.
Binding APIs have been improved to allow more advanced use.
New ReadOnlyHasValue wrapper helps to bind any visible element to a data item via Binder.
Built-in StringTo converters now have an option to use ErrorMessageProvider.
Grid headers and footers now support tooltips.
Added Tree and TreeGrid recursive expand and collapse methods.
BrowserResizeListener is called lazily during the resize.
ItemClickEvent for Grid now takes an additional row index parameter.
Support starting downloads and opening URLs from a MenuItem.
ComboBox supports ConnectorResource icons.

Incompatible or Behavior-altering Changes in 8.4

BrowserWindowOpenerConnector and FileDownloaderConnector now are subclasses of AbstractEventTriggerExtensionConnector.
Date range limits in AbstractDateFieldState are now Strings instead of Dates, some client-side method signatures were changed.
BrowserResizeListener is only called once resizing ends.
ItemClickEvent for Grid now takes an additional row index parameter.