Correctly dispose of Renderer and ScreenDprMonitor

src/renderer/Renderer.ts

@@ -62,12 +62,14 @@ export class Renderer extends EventEmitter implements IRenderer {
     this._renderDebouncer = new RenderDebouncer(this._terminal, this._renderRows.bind(this));
     this._screenDprMonitor = new ScreenDprMonitor();
     this._screenDprMonitor.setListener(() => this.onWindowResize(window.devicePixelRatio));
+    this.register(this._screenDprMonitor);
 
     // Detect whether IntersectionObserver is detected and enable renderer pause
     // and resume based on terminal visibility if so
     if ('IntersectionObserver' in window) {
       const observer = new IntersectionObserver(e => this.onIntersectionChange(e[0]), {threshold: 0});
       observer.observe(this._terminal.element);
+      this.register({ dispose: () => observer.disconnect() });
     }
   }