Reactive Utils

This GeoBlazor sample, written in Blazor for .NET developers, demonstrates the reactiveUtils module from the ArcGIS Maps SDK for JavaScript exposed through GeoBlazor's AddReactiveWatcher, AddReactiveListener, and AddReactiveWaiter methods on SceneView and widget components. The page loads a 3D web scene of Paris into a SceneView with a HomeWidget in the upper-left and a LayerListWidget in the upper-right. Above the scene are three collapsible Accordion sections. The Add Watchers section provides checkboxes to subscribe to popup-open state, the view's center point, the view's extent, the visible-layer list, and a one-time zoom watcher; each prints its current value live as the user pans, zooms, or toggles layers. The Add Listeners section attaches click and drag event listeners that serialize and display each event payload as JSON. The Add Waiters section uses a waiter to detect when the HomeWidget becomes visible and a second checkbox to toggle that visibility. The sample is intended to demonstrate how to bind C# callbacks to reactive ArcGIS view and widget properties in a Blazor application without writing JavaScript.