I have implemented a portal (using AppLayout, Vaadin 14.8.14). While navigating from links from the drawer menu, a portlet (IFrame) is opened as a content.
I want to implement Toggle theme button (on the header of the portal) which changes the portal theme (including portlet theme) from dark to light and vice versa.
I can implement this with sending the theme as a URL parameter and re-navigating to the portlet, but with this implementation the state of the portlet is lost (if the user has populated some data in the portlet, and then wants to switch the theme, the content in the IFrame will be reset).
How can I change the portlet theme from the portal without reloading the portlet?