diff --git a/src/vs/base/browser/dom.ts b/src/vs/base/browser/dom.ts
index 90183d71270..c5f49f198e5 100644
--- a/src/vs/base/browser/dom.ts
+++ b/src/vs/base/browser/dom.ts
@@ -768,6 +768,10 @@ export function findParentWithClass(node: HTMLElement, clazz: string, stopAtClaz
 	return null;
 }
 
+export function hasParentWithClass(node: HTMLElement, clazz: string, stopAtClazzOrNode?: string | HTMLElement): boolean {
+	return !!findParentWithClass(node, clazz, stopAtClazzOrNode);
+}
+
 export function createStyleSheet(container: HTMLElement = document.getElementsByTagName('head')[0]): HTMLStyleElement {
 	let style = document.createElement('style');
 	style.type = 'text/css';
diff --git a/src/vs/base/browser/ui/tree/abstractTree.ts b/src/vs/base/browser/ui/tree/abstractTree.ts
index 19feab47a05..0bda3de3426 100644
--- a/src/vs/base/browser/ui/tree/abstractTree.ts
+++ b/src/vs/base/browser/ui/tree/abstractTree.ts
@@ -7,11 +7,11 @@ import 'vs/css!./media/tree';
 import { IDisposable, dispose, Disposable, toDisposable } from 'vs/base/common/lifecycle';
 import { IListOptions, List, IListStyles, mightProducePrintableCharacter, MouseController } from 'vs/base/browser/ui/list/listWidget';
 import { IListVirtualDelegate, IListRenderer, IListMouseEvent, IListEvent, IListContextMenuEvent, IListDragAndDrop, IListDragOverReaction, IKeyboardNavigationLabelProvider, IIdentityProvider } from 'vs/base/browser/ui/list/list';
-import { append, $, toggleClass, getDomNodePagePosition, removeClass, addClass, hasClass } from 'vs/base/browser/dom';
+import { append, $, toggleClass, getDomNodePagePosition, removeClass, addClass, hasClass, hasParentWithClass } from 'vs/base/browser/dom';
 import { Event, Relay, Emitter, EventBufferer } from 'vs/base/common/event';
 import { StandardKeyboardEvent, IKeyboardEvent } from 'vs/base/browser/keyboardEvent';
 import { KeyCode } from 'vs/base/common/keyCodes';
-import { ITreeModel, ITreeNode, ITreeRenderer, ITreeEvent, ITreeMouseEvent, ITreeContextMenuEvent, ITreeFilter, ITreeNavigator, ICollapseStateChangeEvent, ITreeDragAndDrop, TreeDragOverBubble, TreeVisibility, TreeFilterResult, ITreeModelSpliceEvent } from 'vs/base/browser/ui/tree/tree';
+import { ITreeModel, ITreeNode, ITreeRenderer, ITreeEvent, ITreeMouseEvent, ITreeContextMenuEvent, ITreeFilter, ITreeNavigator, ICollapseStateChangeEvent, ITreeDragAndDrop, TreeDragOverBubble, TreeVisibility, TreeFilterResult, ITreeModelSpliceEvent, TreeMouseEventTarget } from 'vs/base/browser/ui/tree/tree';
 import { ISpliceable } from 'vs/base/common/sequence';
 import { IDragAndDropData, StaticDND, DragAndDropData } from 'vs/base/browser/dnd';
 import { range, equals, distinctES6 } from 'vs/base/common/arrays';
@@ -722,9 +722,18 @@ function asTreeEvent<T>(event: IListEvent<ITreeNode<T, any>>): ITreeEvent<T> {
 }
 
 function asTreeMouseEvent<T>(event: IListMouseEvent<ITreeNode<T, any>>): ITreeMouseEvent<T> {
+	let target: TreeMouseEventTarget = TreeMouseEventTarget.Unknown;
+
+	if (hasParentWithClass(event.browserEvent.target as HTMLElement, 'monaco-tl-twistie', 'monaco-tl-row')) {
+		target = TreeMouseEventTarget.Twistie;
+	} else if (hasParentWithClass(event.browserEvent.target as HTMLElement, 'monaco-tl-contents', 'monaco-tl-row')) {
+		target = TreeMouseEventTarget.Element;
+	}
+
 	return {
 		browserEvent: event.browserEvent,
-		element: event.element ? event.element.element : null
+		element: event.element ? event.element.element : null,
+		target
 	};
 }
 
diff --git a/src/vs/base/browser/ui/tree/asyncDataTree.ts b/src/vs/base/browser/ui/tree/asyncDataTree.ts
index d5a9fc72915..70beeb2145d 100644
--- a/src/vs/base/browser/ui/tree/asyncDataTree.ts
+++ b/src/vs/base/browser/ui/tree/asyncDataTree.ts
@@ -133,7 +133,8 @@ function asTreeEvent<TInput, T>(e: ITreeEvent<IAsyncDataTreeNode<TInput, T>>): I
 function asTreeMouseEvent<TInput, T>(e: ITreeMouseEvent<IAsyncDataTreeNode<TInput, T>>): ITreeMouseEvent<T> {
 	return {
 		browserEvent: e.browserEvent,
-		element: e.element && e.element.element as T
+		element: e.element && e.element.element as T,
+		target: e.target
 	};
 }
 
diff --git a/src/vs/base/browser/ui/tree/tree.ts b/src/vs/base/browser/ui/tree/tree.ts
index cedb6fbd423..80b30fa4c55 100644
--- a/src/vs/base/browser/ui/tree/tree.ts
+++ b/src/vs/base/browser/ui/tree/tree.ts
@@ -137,9 +137,16 @@ export interface ITreeEvent<T> {
 	browserEvent?: UIEvent;
 }
 
+export enum TreeMouseEventTarget {
+	Unknown,
+	Twistie,
+	Element
+}
+
 export interface ITreeMouseEvent<T> {
 	browserEvent: MouseEvent;
 	element: T | null;
+	target: TreeMouseEventTarget;
 }
 
 export interface ITreeContextMenuEvent<T> {
diff --git a/src/vs/workbench/contrib/callHierarchy/browser/callHierarchyPeek.ts b/src/vs/workbench/contrib/callHierarchy/browser/callHierarchyPeek.ts
index a244ae259cf..677ee37a697 100644
--- a/src/vs/workbench/contrib/callHierarchy/browser/callHierarchyPeek.ts
+++ b/src/vs/workbench/contrib/callHierarchy/browser/callHierarchyPeek.ts
@@ -33,6 +33,7 @@ import { IActionBarOptions, ActionsOrientation } from 'vs/base/browser/ui/action
 import { ILabelService } from 'vs/platform/label/common/label';
 import { IStorageService, StorageScope } from 'vs/platform/storage/common/storage';
 import { Color } from 'vs/base/common/color';
+import { TreeMouseEventTarget } from 'vs/base/browser/ui/tree/tree';
 
 const enum State {
 	Loading = 'loading',
@@ -307,6 +308,10 @@ export class CallHierarchyTreePeekWidget extends PeekViewWidget {
 		}));
 
 		this._disposables.add(this._tree.onMouseDblClick(e => {
+			if (e.target === TreeMouseEventTarget.Twistie) {
+				return;
+			}
+
 			if (e.element && isNonEmptyArray(e.element.locations)) {
 				this.dispose();
 				this._editorService.openEditor({