diff --git a/extension/src/EvaluationWatchService/EvaluationEngine/JsEvaluationEngine.ts b/extension/src/EvaluationWatchService/EvaluationEngine/JsEvaluationEngine.ts
index c9703e6..dc95c6f 100644
--- a/extension/src/EvaluationWatchService/EvaluationEngine/JsEvaluationEngine.ts
+++ b/extension/src/EvaluationWatchService/EvaluationEngine/JsEvaluationEngine.ts
@@ -25,6 +25,7 @@ export class JsEvaluationEngine implements EvaluationEngine {
 			"extensionHost",
 			"chrome",
 			"pwa-chrome",
+			"pwa-node",
 		];
 		if (supportedDebugAdapters.indexOf(session.session.type) !== -1) {
 			return new JsEvaluator(session);
@@ -38,6 +39,13 @@ class JsEvaluator implements Evaluator {
 
 	constructor(private readonly session: VsCodeDebugSession) {}
 
+	private getContext(): "copy" | "repl" {
+		if (this.session.session.type.startsWith("pwa-")) {
+			return "copy";
+		}
+		return "repl";
+	}
+
 	public async evaluate({
 		expression,
 		preferredExtractorId,
@@ -75,10 +83,13 @@ class JsEvaluator implements Evaluator {
 				const reply = await this.session.evaluate({
 					expression: wrappedExpr,
 					frameId,
-					context: "repl",
+					context: this.getContext(),
 				});
 				const resultStr = reply.result;
-				const jsonData = resultStr.substr(1, resultStr.length - 2);
+				const jsonData =
+					this.getContext() === "copy"
+						? resultStr
+						: resultStr.substr(1, resultStr.length - 2);
 				const result = JSON.parse(jsonData) as DataResult;
 
 				if (result.kind === "NoExtractors") {
@@ -117,7 +128,7 @@ class JsEvaluator implements Evaluator {
 			await this.session.evaluate({
 				expression,
 				frameId,
-				context: "repl",
+				context: this.getContext(),
 			});
 
 			return true;
diff --git a/extension/src/VsCodeDebugger.ts b/extension/src/VsCodeDebugger.ts
index add35a4..df2e897 100644
--- a/extension/src/VsCodeDebugger.ts
+++ b/extension/src/VsCodeDebugger.ts
@@ -35,9 +35,6 @@ export class VsCodeDebugger {
 				createDebugAdapterTracker: session => {
 					const extendedSession = this.getDebugSession(session);
 					return {
-						onWillReceiveMessage: msg => {
-							console.log(msg.type, msg.event, msg);
-						},
 						onDidSendMessage: async msg => {
 							type Message =
 								| StoppedEvent
@@ -167,7 +164,7 @@ export class VsCodeDebugSession {
 	public async evaluate(args: {
 		expression: string;
 		frameId: number | undefined;
-		context: "watch" | "repl";
+		context: "watch" | "repl" | "copy";
 	}): Promise<{ result: string }> {
 		const reply = await this.session.customRequest("evaluate", {
 			expression: args.expression,
diff --git a/visualization/src/visualizers/AstVisualizer.tsx b/visualization/src/visualizers/AstVisualizer.tsx
index 5c33c2e..2927b11 100644
--- a/visualization/src/visualizers/AstVisualizer.tsx
+++ b/visualization/src/visualizers/AstVisualizer.tsx
@@ -12,7 +12,7 @@ import { createTreeViewModelFromTreeNodeData } from "./TreeVisualizer/TreeVisual
 import { TreeWithPathView, TreeViewModel } from "./TreeVisualizer/Views";
 import * as React from "react";
 import { observer, disposeOnUnmount } from "mobx-react";
-import { observable, autorun, trace } from "mobx";
+import { observable, autorun, trace, computed } from "mobx";
 import * as monaco from "monaco-editor";
 import { getLanguageId } from "./text-visualizers/MonacoTextVisualizer";
 import LineColumn from "line-column";
@@ -115,80 +115,116 @@ export class MonacoEditor extends React.Component<{
 		}
 	}
 
+	@computed.struct
+	private get markedRanges(): monaco.IRange[] {
+		if (!this.editor || !this.model) {
+			return [];
+		}
+
+		const editorModel = this.model;
+		const ranges = this.props.model.marked.map(s =>
+			this.props.nodeInfoToRange(s.data)
+		);
+		return ranges;
+	}
+
 	@disposeOnUnmount
 	private _updateMarkedDecorations = autorun(
 		() => {
-			if (this.editor && this.model) {
-				const editorModel = this.model;
-				const ranges = this.props.model.marked.map(s =>
-					this.props.nodeInfoToRange(s.data)
+			if (!this.editor) {
+				return;
+			}
+			const ranges = this.markedRanges;
+			this.markedDecorations = this.editor.deltaDecorations(
+				this.markedDecorations,
+				ranges.map(range => ({
+					range,
+					options: { className: "marked" },
+				}))
+			);
+			if (ranges.length > 0) {
+				this.editor.revealRange(
+					ranges[0],
+					monaco.editor.ScrollType.Smooth
 				);
-				this.markedDecorations = this.editor.deltaDecorations(
-					this.markedDecorations,
-					ranges.map(range => ({
-						range,
-						options: { className: "marked" },
-					}))
-				);
-				if (ranges.length > 0) {
-					this.editor.revealRange(
-						ranges[0],
-						monaco.editor.ScrollType.Smooth
-					);
-				}
 			}
 		},
 		{ name: "updateMarkedDecorations" }
 	);
 
+	@computed.struct
+	private get selected(): monaco.IRange | undefined {
+		if (this.editor && this.model) {
+			const selected = this.props.model.selected;
+			if (selected) {
+				const range = this.props.nodeInfoToRange(selected.data);
+				return range;
+			}
+		}
+		return undefined;
+	}
+
 	@disposeOnUnmount
 	private _updateSelectedDecoration = autorun(
 		() => {
-			if (this.editor && this.model) {
-				const selected = this.props.model.selected;
-				if (selected) {
-					const range = this.props.nodeInfoToRange(selected.data);
-					this.selectedDecorations = this.editor.deltaDecorations(
-						this.selectedDecorations,
-						[
-							{
-								range,
-								options: { className: "selected" },
-							},
-						]
-					);
-					this.editor.revealRange(
-						range,
-						monaco.editor.ScrollType.Smooth
-					);
-				} else {
-					this.selectedDecorations = this.editor.deltaDecorations(
-						this.selectedDecorations,
-						[]
-					);
-				}
+			console.log("_updateSelectedDecoration");
+			if (!this.editor) {
+				return;
+			}
+			const range = this.selected;
+			if (range) {
+				this.selectedDecorations = this.editor.deltaDecorations(
+					this.selectedDecorations,
+					[
+						{
+							range,
+							options: { className: "selected" },
+						},
+					]
+				);
+				this.editor.revealRange(range, monaco.editor.ScrollType.Smooth);
+			} else {
+				this.selectedDecorations = this.editor.deltaDecorations(
+					this.selectedDecorations,
+					[]
+				);
 			}
 		},
 		{ name: "updateDecorations" }
 	);
 
+	private test = (() => {
+		console.log("test created");
+	})();
+
+	@computed.struct
+	private get modelData(): { text: string; languageId: string } {
+		const { text, languageId } = this.props;
+		return { text, languageId };
+	}
+
 	@disposeOnUnmount
-	private _updateText = autorun(() => {
-		if (this.editor) {
-			const model = monaco.editor.createModel(
-				this.props.text,
-				this.props.languageId,
-				undefined
-			);
+	private _updateText = autorun(
+		() => {
+			console.log("_updateText rerun");
+			if (this.editor) {
+				const model = monaco.editor.createModel(
+					this.modelData.text,
+					this.modelData.languageId,
+					undefined
+				);
 
-			this.editor.setModel(model);
+				this.editor.setModel(model);
 
-			if (this.modelNotObservable) {
-				this.modelNotObservable.dispose();
+				if (this.modelNotObservable) {
+					this.modelNotObservable.dispose();
+				}
+				this.modelNotObservable = model;
+				this.model = model;
 			}
-			this.model = model;
-		}
-	});
+		},
+		{ name: "Update Model" }
+	);
 
 	private readonly setEditorDiv = (editorDiv: HTMLDivElement) => {
 		if (!editorDiv) {
diff --git a/webview/package.json b/webview/package.json
index ac20c23..65808f2 100644
--- a/webview/package.json
+++ b/webview/package.json
@@ -19,7 +19,8 @@
 		"react": "^16.12.0",
 		"react-dom": "^16.12.0",
 		"react-measure": "^2.3.0",
-		"@hediet/debug-visualizer-data-extraction": "*"
+		"@hediet/debug-visualizer-data-extraction": "*",
+		"@knuddels/mobx-logger": "^1.1.1"
 	},
 	"devDependencies": {
 		"@types/html-webpack-plugin": "^3.2.2",
diff --git a/webview/src/components/GUI.tsx b/webview/src/components/GUI.tsx
index 3678cbd..010799a 100644
--- a/webview/src/components/GUI.tsx
+++ b/webview/src/components/GUI.tsx
@@ -103,19 +103,20 @@ export class VisualizerHeaderMain extends React.Component<{ model: Model }> {
 					<ExpressionInput model={m} />
 				</div>
 				<div style={{ width: 4 }} />
-				{m.loading ? (
-					<div style={{ padding: "0 4px" }}>
-						<Spinner size={Spinner.SIZE_SMALL} />
-					</div>
-				) : (
-					<Button
-						minimal
-						small
-						className="part-Icon"
-						icon="refresh"
-						onClick={() => m.refresh()}
-					/>
-				)}
+				{!m.isPolling &&
+					(m.loading ? (
+						<div style={{ padding: "0 4px" }}>
+							<Spinner size={Spinner.SIZE_SMALL} />
+						</div>
+					) : (
+						<Button
+							minimal
+							small
+							className="part-Icon"
+							icon="refresh"
+							onClick={() => m.refresh()}
+						/>
+					))}
 				<Button
 					minimal
 					small
diff --git a/webview/src/components/VisualizerHeaderDetails.tsx b/webview/src/components/VisualizerHeaderDetails.tsx
index ef1ac1f..e416a25 100644
--- a/webview/src/components/VisualizerHeaderDetails.tsx
+++ b/webview/src/components/VisualizerHeaderDetails.tsx
@@ -1,5 +1,5 @@
 import * as React from "react";
-import { Popover } from "@blueprintjs/core";
+import { Popover, Checkbox } from "@blueprintjs/core";
 import { DataExtractorInfo } from "@hediet/debug-visualizer-data-extraction";
 import { computed } from "mobx";
 import { observer } from "mobx-react";
@@ -80,6 +80,12 @@ export class VisualizerHeaderDetails extends React.Component<{ model: Model }> {
 							: []
 					}
 				/>
+				<div style={{ width: 10 }} />
+				<Checkbox
+					label="Poll"
+					checked={m.isPolling}
+					onChange={e => m.setPolling(e.currentTarget.checked)}
+				/>
 			</div>
 		);
 	}
diff --git a/webview/src/index.tsx b/webview/src/index.tsx
index 2892db2..b567caf 100644
--- a/webview/src/index.tsx
+++ b/webview/src/index.tsx
@@ -3,6 +3,7 @@ import * as ReactDOM from "react-dom";
 import "./style.scss";
 import { Model } from "./model/Model";
 import Components = require("./components/GUI");
+import * as mobx from "mobx";
 
 const model = new Model();
 
diff --git a/webview/src/model/Model.ts b/webview/src/model/Model.ts
index 112c84a..217156c 100644
--- a/webview/src/model/Model.ts
+++ b/webview/src/model/Model.ts
@@ -17,7 +17,7 @@ import {
 import { getApi as getVsCodeApi } from "./VsCodeApi";
 import { MonacoBridge } from "./MonacoBridge";
 import { Disposable } from "@hediet/std/disposable";
-import { startInterval } from "@hediet/std/timer";
+import { startInterval, EventTimer } from "@hediet/std/timer";
 
 declare const window: Window & {
 	webViewData?: {
@@ -55,6 +55,11 @@ export class Model {
 		| VisualizationId
 		| undefined = undefined;
 
+	@observable isPolling = false;
+	private readonly pollingTimer = this.dispose.track(
+		new EventTimer(500, "stopped")
+	);
+
 	@action
 	public setPreferredVisualizationId(id: VisualizationId) {
 		this.preferredVisualizationId = id;
@@ -65,6 +70,16 @@ export class Model {
 		this.state = { kind: "visualizationError", data: data };
 	}
 
+	@action
+	public setPolling(value: boolean) {
+		this.isPolling = value;
+		if (value) {
+			this.pollingTimer.start();
+		} else {
+			this.pollingTimer.stop();
+		}
+	}
+
 	@computed get visualizations():
 		| {
 				visualization: Visualization | undefined;
@@ -163,6 +178,10 @@ export class Model {
 				this.setExpression(state.expression);
 			}
 		});
+
+		this.pollingTimer.onTick.sub(() => {
+			this.refresh();
+		});
 	}
 
 	@action
diff --git a/webview/webpack.config.ts b/webview/webpack.config.ts
index 1c1be8b..ac01277 100644
--- a/webview/webpack.config.ts
+++ b/webview/webpack.config.ts
@@ -32,6 +32,14 @@ module.exports = {
 		path: r("dist"),
 		filename: "[name].js",
 		chunkFilename: "[name]-[hash].js",
+		devtoolModuleFilenameTemplate: info => {
+			let result = info.absoluteResourcePath.replace(/\\/g, "/");
+			if (!result.startsWith("file:")) {
+				// Some paths already start with the file scheme.
+				result = "file:///" + result;
+			}
+			return result;
+		},
 	},
 	resolve: {
 		extensions: [".webpack.js", ".web.js", ".ts", ".tsx", ".js"],
diff --git a/yarn.lock b/yarn.lock
index 8507ccd..bde0bcb 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -320,6 +320,11 @@
   resolved "https://registry.yarnpkg.com/@istanbuljs/schema/-/schema-0.1.2.tgz#26520bf09abe4a5644cd5414e37125a8954241dd"
   integrity sha512-tsAQNx32a8CoFhjhijUIhI4kccIAgmGhy8LZMZgGfmXcpMbPRUqn5LWmgRttILi6yeGmBJd2xsPkFMs0PzgPCw==
 
+"@knuddels/mobx-logger@^1.1.1":
+  version "1.1.1"
+  resolved "https://registry.yarnpkg.com/@knuddels/mobx-logger/-/mobx-logger-1.1.1.tgz#64f3d449d5fabfdd710616d668a6d898cc9caa7f"
+  integrity sha512-5iVhsa8e4Gsfg/UbgKGSLOMcZdcjl5usZmpVm50mK/CQgnsjupE6KNS/514VnWcwaW3w38Rv0uherHYhEInDuQ==
+
 "@mapbox/geojson-area@0.2.2":
   version "0.2.2"
   resolved "https://registry.yarnpkg.com/@mapbox/geojson-area/-/geojson-area-0.2.2.tgz#18d7814aa36bf23fbbcc379f8e26a22927debf10"