diff --git a/src/vs/base/parts/tree/browser/treeImpl.ts b/src/vs/base/parts/tree/browser/treeImpl.ts
index a3dd867d168965e3905d088fbc4e322d0b543690..7f2ef37a7d3b089b120bc6a04e58910b9c47b799 100644
--- a/src/vs/base/parts/tree/browser/treeImpl.ts
+++ b/src/vs/base/parts/tree/browser/treeImpl.ts
@@ -57,15 +57,12 @@ export class Tree extends Events.EventEmitter implements _.ITree {
 	private model: Model.TreeModel;
 	private view: View.TreeView;
 
-	get onDOMFocus(): Event<FocusEvent> { return this.view.onDOMFocus; }
-	get onDOMBlur(): Event<FocusEvent> { return this.view.onDOMBlur; }
-
-	private _onDispose: Emitter<void> = new Emitter<void>();
-	get onDispose(): Event<void> { return this._onDispose.event; }
+	private _onDispose: Emitter<void>;
 
 	constructor(container: HTMLElement, configuration: _.ITreeConfiguration, options: _.ITreeOptions = {}) {
 		super();
 
+		this._onDispose = new Emitter<void>();
 		this.container = container;
 		this.configuration = configuration;
 		this.options = options;
@@ -87,6 +84,18 @@ export class Tree extends Events.EventEmitter implements _.ITree {
 		this.addEmitter2(this.view);
 	}
 
+	get onDOMFocus(): Event<FocusEvent> {
+		return this.view && this.view.onDOMFocus;
+	}
+
+	get onDOMBlur(): Event<FocusEvent> {
+		return this.view && this.view.onDOMBlur;
+	}
+
+	get onDispose(): Event<void> {
+		return this._onDispose && this._onDispose.event;
+	}
+
 	public getHTMLElement(): HTMLElement {
 		return this.view.getHTMLElement();
 	}
diff --git a/src/vs/workbench/parts/debug/browser/media/debug.contribution.css b/src/vs/workbench/parts/debug/browser/media/debug.contribution.css
index 45f9f3e4028d4914304d5fc448cad64997fa6c41..de5b96b7d098e524240c9f1f57e768eac561f060 100644
--- a/src/vs/workbench/parts/debug/browser/media/debug.contribution.css
+++ b/src/vs/workbench/parts/debug/browser/media/debug.contribution.css
@@ -52,10 +52,10 @@
 }
 
 .monaco-editor .debug-breakpoint-column::before {
-    content: " ";
-    width: 0.9em;
-    height: 0.8em;
-    display: inline-block;
+	content: " ";
+	width: 0.9em;
+	height: 0.8em;
+	display: inline-block;
 	margin-right: 2px;
 	margin-left: 2px;
 	background-size: 110% !important;