So if synchronize doesn’t fit your needs or has limitations with the used component… instead of accessing the property… the component is highly likely also having an event that’s thrown when the active index changes or? This could be intercepted and used to get the value on the server and store it https://github.com/vaadin/flow-components/blob/0b2ee17fd8dcc3646314abe588ad84d68d29bb8b/vaadin-dialog-flow-parent/vaadin-dialog-flow/src/main/java/com/vaadin/flow/component/dialog/Dialog.java#L149