POC: highlight center on hover

packages/excalidraw/components/App.tsx

@@ -2072,6 +2072,7 @@ class App extends React.Component<AppProps, AppState> {
                           />
                         )}
                         <InteractiveCanvas
+                          app={this}
                           containerRef={this.excalidrawContainerRef}
                           canvas={this.interactiveCanvas}
                           elementsMap={elementsMap}