diff --git a/extensions/git/package.json b/extensions/git/package.json
index 2a92f71671228d4812112de1554a0700b0f136ce..9cee78f096b5696f9d7f3202570a38f97a0c359b 100644
--- a/extensions/git/package.json
+++ b/extensions/git/package.json
@@ -1139,11 +1139,6 @@
           "when": "scmProvider == git && scmResourceGroup == workingTree",
           "group": "2_view"
         },
-        {
-          "command": "git.openChange",
-          "when": "scmProvider == git && scmResourceGroup == workingTree",
-          "group": "navigation"
-        },
         {
           "command": "git.openChange",
           "when": "scmProvider == git && scmResourceGroup == untracked",
diff --git a/package.json b/package.json
index 5baee5dd59c8c04ec14f16eed3c6c37d7605c18a..9595c9037ee6d04f3c40cf1d5c04c049103e32d4 100644
--- a/package.json
+++ b/package.json
@@ -70,6 +70,8 @@
     "@types/node": "^10.12.12",
     "@types/semver": "^5.5.0",
     "@types/sinon": "^1.16.36",
+    "@types/yauzl": "^2.9.1",
+    "@types/yazl": "^2.4.2",
     "@types/webpack": "^4.4.10",
     "@types/winreg": "^1.2.30",
     "ansi-colors": "^3.2.3",
diff --git a/src/tsconfig.monaco.json b/src/tsconfig.monaco.json
index aa0af48b342b88aa74f80f88297a6bc06620c1a2..a6430a44ccb82112224abba696297e2daa99c5d1 100644
--- a/src/tsconfig.monaco.json
+++ b/src/tsconfig.monaco.json
@@ -14,7 +14,6 @@
 	},
 	"include": [
 		"typings/require.d.ts",
-		"typings/require-monaco.d.ts",
 		"typings/thenable.d.ts",
 		"typings/es6-promise.d.ts",
 		"typings/lib.es2018.promise.d.ts",
diff --git a/src/typings/require.d.ts b/src/typings/require.d.ts
index 0d8aa16d726343659a1cabbd2b039daff8dd3110..733da26c9adfb2f25d6403c41ebcf9026214f74a 100644
--- a/src/typings/require.d.ts
+++ b/src/typings/require.d.ts
@@ -48,3 +48,5 @@ interface NodeRequire {
 	__$__nodeRequire<T>(moduleName: string): T;
 	getStats(): ReadonlyArray<LoaderEvent>;
 }
+
+declare var require: NodeRequire;
diff --git a/src/typings/yauzl.d.ts b/src/typings/yauzl.d.ts
deleted file mode 100644
index 39ef2ad9488e2460719e22da7d653e1bc334d558..0000000000000000000000000000000000000000
--- a/src/typings/yauzl.d.ts
+++ /dev/null
@@ -1,49 +0,0 @@
-/*---------------------------------------------------------------------------------------------
- *  Copyright (c) Microsoft Corporation. All rights reserved.
- *  Licensed under the MIT License. See License.txt in the project root for license information.
- *--------------------------------------------------------------------------------------------*/
-
-declare module 'yauzl' {
-
-	import { EventEmitter } from 'events';
-	import { Readable } from 'stream';
-
-	export class Entry {
-		fileName: string;
-		extraFields: { id: number; data: Buffer; }[];
-		comment: string;
-		versionMadeBy: number;
-		versionNeededToExtract: number;
-		generalPurposeBitFlag: number;
-		compressionMethod: number;
-		lastModFileTime: number;
-		lastModFileDate: number;
-		crc32: number;
-		compressedSize: number;
-		uncompressedSize: number;
-		fileNameLength: number;
-		extraFieldLength: number;
-		fileCommentLength: number;
-		internalFileAttributes: number;
-		externalFileAttributes: number;
-		relativeOffsetOfLocalHeader: number;
-		getLastModDate(): Date;
-	}
-
-	export class ZipFile extends EventEmitter {
-		readEntry(): void;
-		openReadStream(entry: Entry, callback: (err?: Error, stream?: Readable) => void): void;
-		close(): void;
-		isOpen: boolean;
-		entryCount: number;
-		comment: string;
-	}
-
-	export interface IOptions {
-		autoClose?: boolean;
-		lazyEntries?: boolean;
-	}
-
-	export function open(path: string, callback: (err?: Error, zipfile?: ZipFile) => void): void;
-	export function open(path: string, options: IOptions | undefined, callback: (err?: Error, zipfile?: ZipFile) => void): void;
-}
\ No newline at end of file
diff --git a/src/typings/yazl.d.ts b/src/typings/yazl.d.ts
deleted file mode 100644
index 5644d092913ef480ce72314190383627ef9e1a41..0000000000000000000000000000000000000000
--- a/src/typings/yazl.d.ts
+++ /dev/null
@@ -1,15 +0,0 @@
-/*---------------------------------------------------------------------------------------------
- *  Copyright (c) Microsoft Corporation. All rights reserved.
- *  Licensed under the MIT License. See License.txt in the project root for license information.
- *--------------------------------------------------------------------------------------------*/
-
-declare module 'yazl' {
-	import * as stream from 'stream';
-
-	class ZipFile {
-		outputStream: stream.Stream;
-		addBuffer(buffer: Buffer, path: string): void;
-		addFile(localPath: string, path: string): void;
-		end(): void;
-	}
-}
\ No newline at end of file
diff --git a/src/vs/base/browser/ui/tree/media/tree.css b/src/vs/base/browser/ui/tree/media/tree.css
index 49acc994b208f3eb011193b431c5eb9842fe9dbf..dc83adc86f408f19f83670f3b7da62e0aab8162d 100644
--- a/src/vs/base/browser/ui/tree/media/tree.css
+++ b/src/vs/base/browser/ui/tree/media/tree.css
@@ -14,7 +14,7 @@
 	height: 100%;
 	position: absolute;
 	top: 0;
-	left: 18px;
+	left: 16px;
 	pointer-events: none;
 }
 
diff --git a/src/vs/base/node/zip.ts b/src/vs/base/node/zip.ts
index eaa6fa36ff81f2411a49a599d864ccaf08714802..93ebb6ad6075690868b810e8feaf09eae760de66 100644
--- a/src/vs/base/node/zip.ts
+++ b/src/vs/base/node/zip.ts
@@ -163,7 +163,7 @@ function extractZip(zipfile: ZipFile, targetPath: string, options: IOptions, tok
 
 function openZip(zipFile: string, lazy: boolean = false): Promise<ZipFile> {
 	return new Promise((resolve, reject) => {
-		_openZip(zipFile, lazy ? { lazyEntries: true } : undefined, (error?: Error, zipfile?: ZipFile) => {
+		_openZip(zipFile, lazy ? { lazyEntries: true } : undefined!, (error?: Error, zipfile?: ZipFile) => {
 			if (error) {
 				reject(toExtractError(error));
 			} else {
diff --git a/src/vs/workbench/api/browser/mainThreadLanguageFeatures.ts b/src/vs/workbench/api/browser/mainThreadLanguageFeatures.ts
index bbec87911f9c032a9ff306b5db2f2f5c9089a0ee..c00e6162bcb2ef0a537b065dbaf00abb7a71e503 100644
--- a/src/vs/workbench/api/browser/mainThreadLanguageFeatures.ts
+++ b/src/vs/workbench/api/browser/mainThreadLanguageFeatures.ts
@@ -498,39 +498,35 @@ export class MainThreadLanguageFeatures implements MainThreadLanguageFeaturesSha
 		this._registrations.set(handle, callh.CallHierarchyProviderRegistry.register(selector, {
 
 			prepareCallHierarchy: async (document, position, token) => {
-				const result = await this._proxy.$prepareCallHierarchy(handle, document.uri, position, token);
-				if (!result) {
+				const item = await this._proxy.$prepareCallHierarchy(handle, document.uri, position, token);
+				if (!item) {
 					return undefined;
 				}
 				return {
-					dispose: () => this._proxy.$releaseCallHierarchy(handle, result.sessionId),
-					root: MainThreadLanguageFeatures._reviveCallHierarchyItemDto(result.root)
+					dispose: () => this._proxy.$releaseCallHierarchy(handle, item._sessionId),
+					root: MainThreadLanguageFeatures._reviveCallHierarchyItemDto(item)
 				};
 			},
 
 			provideOutgoingCalls: async (item, token) => {
-				const outgoing = await this._proxy.$provideCallHierarchyOutgoingCalls(handle, item.id, token);
+				const outgoing = await this._proxy.$provideCallHierarchyOutgoingCalls(handle, item._sessionId, item._itemId, token);
 				if (!outgoing) {
 					return outgoing;
 				}
-				return outgoing.map(([item, fromRanges]): callh.OutgoingCall => {
-					return {
-						to: MainThreadLanguageFeatures._reviveCallHierarchyItemDto(item),
-						fromRanges
-					};
+				outgoing.forEach(value => {
+					value.to = MainThreadLanguageFeatures._reviveCallHierarchyItemDto(value.to);
 				});
+				return <any>outgoing;
 			},
 			provideIncomingCalls: async (item, token) => {
-				const incoming = await this._proxy.$provideCallHierarchyIncomingCalls(handle, item.id, token);
+				const incoming = await this._proxy.$provideCallHierarchyIncomingCalls(handle, item._sessionId, item._itemId, token);
 				if (!incoming) {
 					return incoming;
 				}
-				return incoming.map(([item, fromRanges]): callh.IncomingCall => {
-					return {
-						from: MainThreadLanguageFeatures._reviveCallHierarchyItemDto(item),
-						fromRanges
-					};
+				incoming.forEach(value => {
+					value.from = MainThreadLanguageFeatures._reviveCallHierarchyItemDto(value.from);
 				});
+				return <any>incoming;
 			}
 		}));
 	}
diff --git a/src/vs/workbench/api/common/extHost.protocol.ts b/src/vs/workbench/api/common/extHost.protocol.ts
index 6c6364cf730770765eab544cf2626676a39d1806..63da5a6a6b2053aec586395522ef63d17c4b7e35 100644
--- a/src/vs/workbench/api/common/extHost.protocol.ts
+++ b/src/vs/workbench/api/common/extHost.protocol.ts
@@ -71,7 +71,7 @@ export interface IStaticWorkspaceData {
 }
 
 export interface IWorkspaceData extends IStaticWorkspaceData {
-	folders: { uri: UriComponents, name: string, index: number }[];
+	folders: { uri: UriComponents, name: string, index: number; }[];
 }
 
 export interface IInitData {
@@ -97,7 +97,7 @@ export interface IConfigurationInitData extends IConfigurationData {
 
 export interface IWorkspaceConfigurationChangeEventData {
 	changedConfiguration: IConfigurationModel;
-	changedConfigurationByResource: { [folder: string]: IConfigurationModel };
+	changedConfigurationByResource: { [folder: string]: IConfigurationModel; };
 }
 
 export interface IExtHostContext extends IRPCProtocol {
@@ -136,7 +136,7 @@ export type CommentThreadChanges = Partial<{
 	label: string,
 	contextValue: string,
 	comments: modes.Comment[],
-	collapseState: modes.CommentThreadCollapsibleState
+	collapseState: modes.CommentThreadCollapsibleState;
 }>;
 
 export interface MainThreadCommentsShape extends IDisposable {
@@ -165,13 +165,13 @@ export interface MainThreadDialogOpenOptions {
 	canSelectFiles?: boolean;
 	canSelectFolders?: boolean;
 	canSelectMany?: boolean;
-	filters?: { [name: string]: string[] };
+	filters?: { [name: string]: string[]; };
 }
 
 export interface MainThreadDialogSaveOptions {
 	defaultUri?: UriComponents;
 	saveLabel?: string;
-	filters?: { [name: string]: string[] };
+	filters?: { [name: string]: string[]; };
 }
 
 export interface MainThreadDiaglogsShape extends IDisposable {
@@ -254,8 +254,8 @@ export interface MainThreadTextEditorsShape extends IDisposable {
 }
 
 export interface MainThreadTreeViewsShape extends IDisposable {
-	$registerTreeViewDataProvider(treeViewId: string, options: { showCollapseAll: boolean, canSelectMany: boolean }): void;
-	$refresh(treeViewId: string, itemsToRefresh?: { [treeItemHandle: string]: ITreeItem }): Promise<void>;
+	$registerTreeViewDataProvider(treeViewId: string, options: { showCollapseAll: boolean, canSelectMany: boolean; }): void;
+	$refresh(treeViewId: string, itemsToRefresh?: { [treeItemHandle: string]: ITreeItem; }): Promise<void>;
 	$reveal(treeViewId: string, treeItem: ITreeItem, parentChain: ITreeItem[], options: IRevealOptions): Promise<void>;
 	$setMessage(treeViewId: string, message: string): void;
 	$setTitle(treeViewId: string, title: string): void;
@@ -278,7 +278,7 @@ export interface MainThreadKeytarShape extends IDisposable {
 	$setPassword(service: string, account: string, password: string): Promise<void>;
 	$deletePassword(service: string, account: string): Promise<boolean>;
 	$findPassword(service: string): Promise<string | null>;
-	$findCredentials(service: string): Promise<Array<{ account: string, password: string }>>;
+	$findCredentials(service: string): Promise<Array<{ account: string, password: string; }>>;
 }
 
 export interface IRegExpDto {
@@ -321,7 +321,7 @@ export interface ILanguageConfigurationDto {
 	};
 }
 
-export type GlobPattern = string | { base: string; pattern: string };
+export type GlobPattern = string | { base: string; pattern: string; };
 
 export interface IDocumentFilterDto {
 	$serialized: true;
@@ -400,7 +400,7 @@ export interface TerminalLaunchConfig {
 	shellPath?: string;
 	shellArgs?: string[] | string;
 	cwd?: string | UriComponents;
-	env?: { [key: string]: string | null };
+	env?: { [key: string]: string | null; };
 	waitOnExit?: boolean;
 	strictEnv?: boolean;
 	hideFromUser?: boolean;
@@ -408,7 +408,7 @@ export interface TerminalLaunchConfig {
 }
 
 export interface MainThreadTerminalServiceShape extends IDisposable {
-	$createTerminal(config: TerminalLaunchConfig): Promise<{ id: number, name: string }>;
+	$createTerminal(config: TerminalLaunchConfig): Promise<{ id: number, name: string; }>;
 	$dispose(terminalId: number): void;
 	$hide(terminalId: number): void;
 	$sendText(terminalId: number, text: string, addNewLine: boolean): void;
@@ -558,7 +558,7 @@ export interface MainThreadWebviewsShape extends IDisposable {
 	$disposeWebview(handle: WebviewPanelHandle): void;
 	$reveal(handle: WebviewPanelHandle, showOptions: WebviewPanelShowOptions): void;
 	$setTitle(handle: WebviewPanelHandle, value: string): void;
-	$setIconPath(handle: WebviewPanelHandle, value: { light: UriComponents, dark: UriComponents } | undefined): void;
+	$setIconPath(handle: WebviewPanelHandle, value: { light: UriComponents, dark: UriComponents; } | undefined): void;
 
 	$setHtml(handle: WebviewPanelHandle, value: string): void;
 	$setOptions(handle: WebviewPanelHandle, options: modes.IWebviewOptions): void;
@@ -593,7 +593,7 @@ export interface MainThreadUrlsShape extends IDisposable {
 	$registerUriHandler(handle: number, extensionId: ExtensionIdentifier): Promise<void>;
 	$unregisterUriHandler(handle: number): Promise<void>;
 	$createAppUri(uri: UriComponents): Promise<UriComponents>;
-	$proposedCreateAppUri(extensionId: ExtensionIdentifier, options?: { payload?: Partial<UriComponents> }): Promise<UriComponents>;
+	$proposedCreateAppUri(extensionId: ExtensionIdentifier, options?: { payload?: Partial<UriComponents>; }): Promise<UriComponents>;
 }
 
 export interface ExtHostUrlsShape {
@@ -609,7 +609,7 @@ export interface MainThreadWorkspaceShape extends IDisposable {
 	$startTextSearch(query: search.IPatternInfo, options: ITextQueryBuilderOptions, requestId: number, token: CancellationToken): Promise<ITextSearchComplete>;
 	$checkExists(folders: UriComponents[], includes: string[], token: CancellationToken): Promise<boolean>;
 	$saveAll(includeUntitled?: boolean): Promise<boolean>;
-	$updateWorkspaceFolders(extensionName: string, index: number, deleteCount: number, workspaceFoldersToAdd: { uri: UriComponents, name?: string }[]): Promise<void>;
+	$updateWorkspaceFolders(extensionName: string, index: number, deleteCount: number, workspaceFoldersToAdd: { uri: UriComponents, name?: string; }[]): Promise<void>;
 	$resolveProxy(url: string): Promise<string | undefined>;
 }
 
@@ -764,7 +764,7 @@ export interface MainThreadWindowShape extends IDisposable {
 
 export interface ExtHostCommandsShape {
 	$executeContributedCommand<T>(id: string, ...args: any[]): Promise<T>;
-	$getContributedCommandHandlerDescriptions(): Promise<{ [id: string]: string | ICommandHandlerDescription }>;
+	$getContributedCommandHandlerDescriptions(): Promise<{ [id: string]: string | ICommandHandlerDescription; }>;
 }
 
 export interface ExtHostConfigurationShape {
@@ -898,7 +898,7 @@ export interface ExtHostExtensionServiceShape {
 	$startExtensionHost(enabledExtensionIds: ExtensionIdentifier[]): Promise<void>;
 	$activateByEvent(activationEvent: string): Promise<void>;
 	$activate(extensionId: ExtensionIdentifier, reason: ExtensionActivationReason): Promise<boolean>;
-	$setRemoteEnvironment(env: { [key: string]: string | null }): Promise<void>;
+	$setRemoteEnvironment(env: { [key: string]: string | null; }): Promise<void>;
 
 	$deltaExtensions(toAdd: IExtensionDescription[], toRemove: ExtensionIdentifier[]): Promise<void>;
 
@@ -978,7 +978,7 @@ export interface ISuggestDataDto {
 	[ISuggestDataDtoField.preselect]?: boolean;
 	[ISuggestDataDtoField.insertText]?: string;
 	[ISuggestDataDtoField.insertTextRules]?: modes.CompletionItemInsertTextRule;
-	[ISuggestDataDtoField.range]?: IRange | { insert: IRange, replace: IRange };
+	[ISuggestDataDtoField.range]?: IRange | { insert: IRange, replace: IRange; };
 	[ISuggestDataDtoField.commitCharacters]?: string[];
 	[ISuggestDataDtoField.additionalTextEdits]?: ISingleEditOperation[];
 	[ISuggestDataDtoField.command]?: modes.Command;
@@ -989,7 +989,7 @@ export interface ISuggestDataDto {
 
 export interface ISuggestResultDto {
 	x?: number;
-	a: { insert: IRange, replace: IRange };
+	a: { insert: IRange, replace: IRange; };
 	b: ISuggestDataDto[];
 	c?: boolean;
 }
@@ -1112,7 +1112,8 @@ export interface ICodeLensDto {
 }
 
 export interface ICallHierarchyItemDto {
-	id: string;
+	_sessionId: string;
+	_itemId: string;
 	kind: modes.SymbolKind;
 	name: string;
 	detail?: string;
@@ -1121,6 +1122,16 @@ export interface ICallHierarchyItemDto {
 	selectionRange: IRange;
 }
 
+export interface IIncomingCallDto {
+	from: ICallHierarchyItemDto;
+	fromRanges: IRange[];
+}
+
+export interface IOutgoingCallDto {
+	fromRanges: IRange[];
+	to: ICallHierarchyItemDto;
+}
+
 export interface ExtHostLanguageFeaturesShape {
 	$provideDocumentSymbols(handle: number, resource: UriComponents, token: CancellationToken): Promise<modes.DocumentSymbol[] | undefined>;
 	$provideCodeLenses(handle: number, resource: UriComponents, token: CancellationToken): Promise<ICodeLensListDto | undefined>;
@@ -1155,9 +1166,9 @@ export interface ExtHostLanguageFeaturesShape {
 	$provideColorPresentations(handle: number, resource: UriComponents, colorInfo: IRawColorInfo, token: CancellationToken): Promise<modes.IColorPresentation[] | undefined>;
 	$provideFoldingRanges(handle: number, resource: UriComponents, context: modes.FoldingContext, token: CancellationToken): Promise<modes.FoldingRange[] | undefined>;
 	$provideSelectionRanges(handle: number, resource: UriComponents, positions: IPosition[], token: CancellationToken): Promise<modes.SelectionRange[][]>;
-	$prepareCallHierarchy(handle: number, resource: UriComponents, position: IPosition, token: CancellationToken): Promise<{ sessionId: string, root: ICallHierarchyItemDto } | undefined>;
-	$provideCallHierarchyIncomingCalls(handle: number, itemId: string, token: CancellationToken): Promise<[ICallHierarchyItemDto, IRange[]][] | undefined>;
-	$provideCallHierarchyOutgoingCalls(handle: number, itemId: string, token: CancellationToken): Promise<[ICallHierarchyItemDto, IRange[]][] | undefined>;
+	$prepareCallHierarchy(handle: number, resource: UriComponents, position: IPosition, token: CancellationToken): Promise<ICallHierarchyItemDto | undefined>;
+	$provideCallHierarchyIncomingCalls(handle: number, sessionId: string, itemId: string, token: CancellationToken): Promise<IIncomingCallDto[] | undefined>;
+	$provideCallHierarchyOutgoingCalls(handle: number, sessionId: string, itemId: string, token: CancellationToken): Promise<IOutgoingCallDto[] | undefined>;
 	$releaseCallHierarchy(handle: number, sessionId: string): void;
 }
 
@@ -1177,7 +1188,7 @@ export interface IShellLaunchConfigDto {
 	executable?: string;
 	args?: string[] | string;
 	cwd?: string | UriComponents;
-	env?: { [key: string]: string | null };
+	env?: { [key: string]: string | null; };
 }
 
 export interface IShellDefinitionDto {
@@ -1232,8 +1243,8 @@ export interface ExtHostTaskShape {
 	$onDidStartTaskProcess(value: tasks.TaskProcessStartedDTO): void;
 	$onDidEndTaskProcess(value: tasks.TaskProcessEndedDTO): void;
 	$OnDidEndTask(execution: tasks.TaskExecutionDTO): void;
-	$resolveVariables(workspaceFolder: UriComponents, toResolve: { process?: { name: string; cwd?: string }, variables: string[] }): Promise<{ process?: string; variables: { [key: string]: string } }>;
-	$getDefaultShellAndArgs(): Thenable<{ shell: string, args: string[] | string | undefined }>;
+	$resolveVariables(workspaceFolder: UriComponents, toResolve: { process?: { name: string; cwd?: string; }, variables: string[]; }): Promise<{ process?: string; variables: { [key: string]: string; }; }>;
+	$getDefaultShellAndArgs(): Thenable<{ shell: string, args: string[] | string | undefined; }>;
 	$jsonTasksSupported(): Thenable<boolean>;
 }
 
@@ -1321,7 +1332,7 @@ export interface DecorationRequest {
 }
 
 export type DecorationData = [number, boolean, string, string, ThemeColor];
-export type DecorationReply = { [id: number]: DecorationData };
+export type DecorationReply = { [id: number]: DecorationData; };
 
 export interface ExtHostDecorationsShape {
 	$provideDecorations(requests: DecorationRequest[], token: CancellationToken): Promise<DecorationReply>;
diff --git a/src/vs/workbench/api/common/extHostApiCommands.ts b/src/vs/workbench/api/common/extHostApiCommands.ts
index e0ae9e2f5f95a46a4573d6c0cdcb4e68943c815e..67e9ba8669e219ce3634ed21b1d5c1ee698dce8a 100644
--- a/src/vs/workbench/api/common/extHostApiCommands.ts
+++ b/src/vs/workbench/api/common/extHostApiCommands.ts
@@ -4,11 +4,11 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { URI } from 'vs/base/common/uri';
-import { DisposableStore } from 'vs/base/common/lifecycle';
+import { DisposableStore, IDisposable } from 'vs/base/common/lifecycle';
 import * as vscode from 'vscode';
 import * as typeConverters from 'vs/workbench/api/common/extHostTypeConverters';
 import * as types from 'vs/workbench/api/common/extHostTypes';
-import { IRawColorInfo, IWorkspaceEditDto } from 'vs/workbench/api/common/extHost.protocol';
+import { IRawColorInfo, IWorkspaceEditDto, ICallHierarchyItemDto, IIncomingCallDto, IOutgoingCallDto } from 'vs/workbench/api/common/extHost.protocol';
 import { ISingleEditOperation } from 'vs/editor/common/model';
 import * as modes from 'vs/editor/common/modes';
 import * as search from 'vs/workbench/contrib/search/common/search';
@@ -19,10 +19,97 @@ import { ICommandsExecutor, OpenFolderAPICommand, DiffAPICommand, OpenAPICommand
 import { EditorGroupLayout } from 'vs/workbench/services/editor/common/editorGroupsService';
 import { isFalsyOrEmpty } from 'vs/base/common/arrays';
 import { IRange } from 'vs/editor/common/core/range';
+import { IPosition } from 'vs/editor/common/core/position';
+
+//#region --- NEW world
+
+export class ApiCommandArgument<V, O = V> {
+
+	static readonly Uri = new ApiCommandArgument<URI>('uri', 'Uri of a text document', v => URI.isUri(v), v => v);
+	static readonly Position = new ApiCommandArgument<types.Position, IPosition>('position', 'A position in a text document', v => types.Position.isPosition(v), typeConverters.Position.from);
+
+	static readonly CallHierarchyItem = new ApiCommandArgument('item', 'A call hierarchy item', v => v instanceof types.CallHierarchyItem, typeConverters.CallHierarchyItem.to);
+
+	constructor(
+		readonly name: string,
+		readonly description: string,
+		readonly validate: (v: V) => boolean,
+		readonly convert: (v: V) => O
+	) { }
+}
+
+export class ApiCommandResult<V, O = V> {
+
+	constructor(
+		readonly description: string,
+		readonly convert: (v: V) => O
+	) { }
+}
+
+export class ApiCommand {
+
+	constructor(
+		readonly id: string,
+		readonly internalId: string,
+		readonly description: string,
+		readonly args: ApiCommandArgument<any, any>[],
+		readonly result: ApiCommandResult<any, any>
+	) { }
+
+	register(commands: ExtHostCommands): IDisposable {
+
+		return commands.registerCommand(false, this.id, async (...apiArgs) => {
+
+			const internalArgs = this.args.map((arg, i) => {
+				if (!arg.validate(apiArgs[i])) {
+					throw new Error(`Invalid argument '${arg.name}' when running '${this.id}', receieved: ${apiArgs[i]}`);
+				}
+				return arg.convert(apiArgs[i]);
+			});
+
+			const internalResult = await commands.executeCommand(this.internalId, ...internalArgs);
+			return this.result.convert(internalResult);
+		}, undefined, this._getCommandHandlerDesc());
+	}
+
+	private _getCommandHandlerDesc(): ICommandHandlerDescription {
+		return {
+			description: this.description,
+			args: this.args,
+			returns: this.result.description
+		};
+	}
+}
+
+
+const newCommands: ApiCommand[] = [
+	new ApiCommand(
+		'vscode.prepareCallHierarchy', '_executePrepareCallHierarchy', 'Prepare call hierarchy at a position inside a document',
+		[ApiCommandArgument.Uri, ApiCommandArgument.Position],
+		new ApiCommandResult<ICallHierarchyItemDto, types.CallHierarchyItem>('A CallHierarchyItem or undefined', v => typeConverters.CallHierarchyItem.to(v))
+	),
+	new ApiCommand(
+		'vscode.provideIncomingCalls', '_executeProvideIncomingCalls', 'Compute incoming calls for an item',
+		[ApiCommandArgument.CallHierarchyItem],
+		new ApiCommandResult<IIncomingCallDto[], types.CallHierarchyIncomingCall[]>('A CallHierarchyItem or undefined', v => v.map(typeConverters.CallHierarchyIncomingCall.to))
+	),
+	new ApiCommand(
+		'vscode.provideOutgoingCalls', '_executeProvideOutgoingCalls', 'Compute outgoing calls for an item',
+		[ApiCommandArgument.CallHierarchyItem],
+		new ApiCommandResult<IOutgoingCallDto[], types.CallHierarchyOutgoingCall[]>('A CallHierarchyItem or undefined', v => v.map(typeConverters.CallHierarchyOutgoingCall.to))
+	),
+];
+
+
+//#endregion
+
+
+//#region OLD world
 
 export class ExtHostApiCommands {
 
 	static register(commands: ExtHostCommands) {
+		newCommands.forEach(command => command.register(commands));
 		return new ExtHostApiCommands(commands).registerCommands();
 	}
 
@@ -433,7 +520,7 @@ export class ExtHostApiCommands {
 		});
 	}
 
-	private _executeColorPresentationProvider(color: types.Color, context: { uri: URI, range: types.Range }): Promise<types.ColorPresentation[]> {
+	private _executeColorPresentationProvider(color: types.Color, context: { uri: URI, range: types.Range; }): Promise<types.ColorPresentation[]> {
 		const args = {
 			resource: context.uri,
 			color: typeConverters.Color.from(color),
diff --git a/src/vs/workbench/api/common/extHostLanguageFeatures.ts b/src/vs/workbench/api/common/extHostLanguageFeatures.ts
index acb80872268a51888dd7076d51b65f7c62bc830c..ee4043d7860bdbe9469fc0dd600490b848f04921 100644
--- a/src/vs/workbench/api/common/extHostLanguageFeatures.ts
+++ b/src/vs/workbench/api/common/extHostLanguageFeatures.ts
@@ -26,6 +26,7 @@ import { CancellationToken } from 'vs/base/common/cancellation';
 import { ExtensionIdentifier, IExtensionDescription } from 'vs/platform/extensions/common/extensions';
 import { IURITransformer } from 'vs/base/common/uriIpc';
 import { DisposableStore, dispose } from 'vs/base/common/lifecycle';
+import { IdGenerator } from 'vs/base/common/idGenerator';
 
 // --- adapter
 
@@ -751,7 +752,7 @@ class SuggestAdapter {
 		}
 
 		// 'overwrite[Before|After]'-logic
-		let range: vscode.Range | { inserting: vscode.Range, replacing: vscode.Range } | undefined;
+		let range: vscode.Range | { inserting: vscode.Range, replacing: vscode.Range; } | undefined;
 		if (item.textEdit) {
 			range = item.textEdit.range;
 		} else if (item.range) {
@@ -1034,15 +1035,15 @@ class SelectionRangeAdapter {
 
 class CallHierarchyAdapter {
 
-	private _idPool: number = 0;
-	private readonly _cache = new Map<string, vscode.CallHierarchyItem[]>();
+	private readonly _idPool = new IdGenerator('');
+	private readonly _cache = new Map<string, Map<string, vscode.CallHierarchyItem>>();
 
 	constructor(
 		private readonly _documents: ExtHostDocuments,
 		private readonly _provider: vscode.CallHierarchyProvider
 	) { }
 
-	async prepareSession(uri: URI, position: IPosition, token: CancellationToken): Promise<{ sessionId: string, root: extHostProtocol.ICallHierarchyItemDto } | undefined> {
+	async prepareSession(uri: URI, position: IPosition, token: CancellationToken): Promise<extHostProtocol.ICallHierarchyItemDto | undefined> {
 		const doc = this._documents.getDocument(uri);
 		const pos = typeConvert.Position.to(position);
 
@@ -1050,13 +1051,14 @@ class CallHierarchyAdapter {
 		if (!item) {
 			return undefined;
 		}
-		const sessionId = String.fromCharCode(this._idPool++);
-		this._cache.set(sessionId, []);
-		return { sessionId, root: this._cacheAndConvertItem(sessionId, item) };
+		const sessionId = this._idPool.nextId();
+
+		this._cache.set(sessionId, new Map());
+		return this._cacheAndConvertItem(sessionId, item);
 	}
 
-	async provideCallsTo(itemId: string, token: CancellationToken): Promise<[extHostProtocol.ICallHierarchyItemDto, IRange[]][] | undefined> {
-		const item = this._itemFromCache(itemId);
+	async provideCallsTo(sessionId: string, itemId: string, token: CancellationToken): Promise<extHostProtocol.IIncomingCallDto[] | undefined> {
+		const item = this._itemFromCache(sessionId, itemId);
 		if (!item) {
 			throw new Error('missing call hierarchy item');
 		}
@@ -1064,11 +1066,16 @@ class CallHierarchyAdapter {
 		if (!calls) {
 			return undefined;
 		}
-		return calls.map(call => (<[extHostProtocol.ICallHierarchyItemDto, IRange[]]>[this._cacheAndConvertItem(itemId, call.from), call.fromRanges.map(typeConvert.Range.from)]));
+		return calls.map(call => {
+			return {
+				from: this._cacheAndConvertItem(sessionId, call.from),
+				fromRanges: call.fromRanges.map(r => typeConvert.Range.from(r))
+			};
+		});
 	}
 
-	async provideCallsFrom(itemId: string, token: CancellationToken): Promise<[extHostProtocol.ICallHierarchyItemDto, IRange[]][] | undefined> {
-		const item = this._itemFromCache(itemId);
+	async provideCallsFrom(sessionId: string, itemId: string, token: CancellationToken): Promise<extHostProtocol.IOutgoingCallDto[] | undefined> {
+		const item = this._itemFromCache(sessionId, itemId);
 		if (!item) {
 			throw new Error('missing call hierarchy item');
 		}
@@ -1076,7 +1083,12 @@ class CallHierarchyAdapter {
 		if (!calls) {
 			return undefined;
 		}
-		return calls.map(call => (<[extHostProtocol.ICallHierarchyItemDto, IRange[]]>[this._cacheAndConvertItem(itemId, call.to), call.fromRanges.map(typeConvert.Range.from)]));
+		return calls.map(call => {
+			return {
+				to: this._cacheAndConvertItem(sessionId, call.to),
+				fromRanges: call.fromRanges.map(r => typeConvert.Range.from(r))
+			};
+		});
 	}
 
 	releaseSession(sessionId: string): void {
@@ -1085,9 +1097,10 @@ class CallHierarchyAdapter {
 
 	private _cacheAndConvertItem(itemOrSessionId: string, item: vscode.CallHierarchyItem): extHostProtocol.ICallHierarchyItemDto {
 		const sessionId = itemOrSessionId.charAt(0);
-		const array = this._cache.get(sessionId)!;
+		const map = this._cache.get(sessionId)!;
 		const dto: extHostProtocol.ICallHierarchyItemDto = {
-			id: sessionId + String.fromCharCode(array.length),
+			_sessionId: sessionId,
+			_itemId: map.size.toString(36),
 			name: item.name,
 			detail: item.detail,
 			kind: typeConvert.SymbolKind.from(item.kind),
@@ -1095,17 +1108,13 @@ class CallHierarchyAdapter {
 			range: typeConvert.Range.from(item.range),
 			selectionRange: typeConvert.Range.from(item.selectionRange),
 		};
-		array.push(item);
+		map.set(dto._itemId, item);
 		return dto;
 	}
 
-	private _itemFromCache(itemId: string): vscode.CallHierarchyItem | undefined {
-		const sessionId = itemId.charAt(0);
-		const array = this._cache.get(sessionId);
-		if (!array) {
-			return undefined;
-		}
-		return array[itemId.charCodeAt(1)];
+	private _itemFromCache(sessionId: string, itemId: string): vscode.CallHierarchyItem | undefined {
+		const map = this._cache.get(sessionId);
+		return map && map.get(itemId);
 	}
 }
 
@@ -1193,7 +1202,7 @@ export class ExtHostLanguageFeatures implements extHostProtocol.ExtHostLanguageF
 		return ExtHostLanguageFeatures._handlePool++;
 	}
 
-	private _withAdapter<A, R>(handle: number, ctor: { new(...args: any[]): A }, callback: (adapter: A, extension: IExtensionDescription | undefined) => Promise<R>, fallbackValue: R): Promise<R> {
+	private _withAdapter<A, R>(handle: number, ctor: { new(...args: any[]): A; }, callback: (adapter: A, extension: IExtensionDescription | undefined) => Promise<R>, fallbackValue: R): Promise<R> {
 		const data = this._adapter.get(handle);
 		if (!data) {
 			return Promise.resolve(fallbackValue);
@@ -1541,16 +1550,16 @@ export class ExtHostLanguageFeatures implements extHostProtocol.ExtHostLanguageF
 		return this._createDisposable(handle);
 	}
 
-	$prepareCallHierarchy(handle: number, resource: UriComponents, position: IPosition, token: CancellationToken): Promise<{ sessionId: string, root: extHostProtocol.ICallHierarchyItemDto } | undefined> {
+	$prepareCallHierarchy(handle: number, resource: UriComponents, position: IPosition, token: CancellationToken): Promise<extHostProtocol.ICallHierarchyItemDto | undefined> {
 		return this._withAdapter(handle, CallHierarchyAdapter, adapter => Promise.resolve(adapter.prepareSession(URI.revive(resource), position, token)), undefined);
 	}
 
-	$provideCallHierarchyIncomingCalls(handle: number, itemId: string, token: CancellationToken): Promise<[extHostProtocol.ICallHierarchyItemDto, IRange[]][] | undefined> {
-		return this._withAdapter(handle, CallHierarchyAdapter, adapter => adapter.provideCallsTo(itemId, token), undefined);
+	$provideCallHierarchyIncomingCalls(handle: number, sessionId: string, itemId: string, token: CancellationToken): Promise<extHostProtocol.IIncomingCallDto[] | undefined> {
+		return this._withAdapter(handle, CallHierarchyAdapter, adapter => adapter.provideCallsTo(sessionId, itemId, token), undefined);
 	}
 
-	$provideCallHierarchyOutgoingCalls(handle: number, itemId: string, token: CancellationToken): Promise<[extHostProtocol.ICallHierarchyItemDto, IRange[]][] | undefined> {
-		return this._withAdapter(handle, CallHierarchyAdapter, adapter => adapter.provideCallsFrom(itemId, token), undefined);
+	$provideCallHierarchyOutgoingCalls(handle: number, sessionId: string, itemId: string, token: CancellationToken): Promise<extHostProtocol.IOutgoingCallDto[] | undefined> {
+		return this._withAdapter(handle, CallHierarchyAdapter, adapter => adapter.provideCallsFrom(sessionId, itemId, token), undefined);
 	}
 
 	$releaseCallHierarchy(handle: number, sessionId: string): void {
diff --git a/src/vs/workbench/api/common/extHostTypeConverters.ts b/src/vs/workbench/api/common/extHostTypeConverters.ts
index ea12d55450eeafcac87bf4fda55d13bf660a474b..a0671a6e51ef627fb1f11b464d739c86f750d564 100644
--- a/src/vs/workbench/api/common/extHostTypeConverters.ts
+++ b/src/vs/workbench/api/common/extHostTypeConverters.ts
@@ -255,7 +255,7 @@ export namespace MarkdownString {
 		}
 
 		// extract uris into a separate object
-		const resUris: { [href: string]: UriComponents } = Object.create(null);
+		const resUris: { [href: string]: UriComponents; } = Object.create(null);
 		res.uris = resUris;
 
 		const collectUri = (href: string): string => {
@@ -277,7 +277,7 @@ export namespace MarkdownString {
 		return res;
 	}
 
-	function _uriMassage(part: string, bucket: { [n: string]: UriComponents }): string {
+	function _uriMassage(part: string, bucket: { [n: string]: UriComponents; }): string {
 		if (!part) {
 			return part;
 		}
@@ -513,7 +513,7 @@ export namespace WorkspaceEdit {
 
 export namespace SymbolKind {
 
-	const _fromMapping: { [kind: number]: modes.SymbolKind } = Object.create(null);
+	const _fromMapping: { [kind: number]: modes.SymbolKind; } = Object.create(null);
 	_fromMapping[types.SymbolKind.File] = modes.SymbolKind.File;
 	_fromMapping[types.SymbolKind.Module] = modes.SymbolKind.Module;
 	_fromMapping[types.SymbolKind.Namespace] = modes.SymbolKind.Namespace;
@@ -627,8 +627,8 @@ export namespace DocumentSymbol {
 
 export namespace CallHierarchyItem {
 
-	export function to(item: extHostProtocol.ICallHierarchyItemDto): vscode.CallHierarchyItem {
-		return new types.CallHierarchyItem(
+	export function to(item: extHostProtocol.ICallHierarchyItemDto): types.CallHierarchyItem {
+		const result = new types.CallHierarchyItem(
 			SymbolKind.to(item.kind),
 			item.name,
 			item.detail || '',
@@ -636,6 +636,31 @@ export namespace CallHierarchyItem {
 			Range.to(item.range),
 			Range.to(item.selectionRange)
 		);
+
+		result._sessionId = item._sessionId;
+		result._itemId = item._itemId;
+
+		return result;
+	}
+}
+
+export namespace CallHierarchyIncomingCall {
+
+	export function to(item: extHostProtocol.IIncomingCallDto): types.CallHierarchyIncomingCall {
+		return new types.CallHierarchyIncomingCall(
+			CallHierarchyItem.to(item.from),
+			item.fromRanges.map(r => Range.to(r))
+		);
+	}
+}
+
+export namespace CallHierarchyOutgoingCall {
+
+	export function to(item: extHostProtocol.IOutgoingCallDto): types.CallHierarchyOutgoingCall {
+		return new types.CallHierarchyOutgoingCall(
+			CallHierarchyItem.to(item.to),
+			item.fromRanges.map(r => Range.to(r))
+		);
 	}
 }
 
diff --git a/src/vs/workbench/api/common/extHostTypes.ts b/src/vs/workbench/api/common/extHostTypes.ts
index ff4afdb3f049748dfc4583a96927404155b1f13e..158fe11fda7e77262e5e6dbfed26d54487b7329a 100644
--- a/src/vs/workbench/api/common/extHostTypes.ts
+++ b/src/vs/workbench/api/common/extHostTypes.ts
@@ -29,8 +29,8 @@ function es5ClassCompat(target: Function): any {
 @es5ClassCompat
 export class Disposable {
 
-	static from(...inDisposables: { dispose(): any }[]): Disposable {
-		let disposables: ReadonlyArray<{ dispose(): any }> | undefined = inDisposables;
+	static from(...inDisposables: { dispose(): any; }[]): Disposable {
+		let disposables: ReadonlyArray<{ dispose(): any; }> | undefined = inDisposables;
 		return new Disposable(function () {
 			if (disposables) {
 				for (const disposable of disposables) {
@@ -333,9 +333,9 @@ export class Range {
 		return this._start.line === this._end.line;
 	}
 
-	with(change: { start?: Position, end?: Position }): Range;
+	with(change: { start?: Position, end?: Position; }): Range;
 	with(start?: Position, end?: Position): Range;
-	with(startOrChange: Position | undefined | { start?: Position, end?: Position }, end: Position = this.end): Range {
+	with(startOrChange: Position | undefined | { start?: Position, end?: Position; }, end: Position = this.end): Range {
 
 		if (startOrChange === null || end === null) {
 			throw illegalArgument();
@@ -589,15 +589,15 @@ export class WorkspaceEdit implements vscode.WorkspaceEdit {
 
 	private _edits = new Array<IFileOperation | IFileTextEdit>();
 
-	renameFile(from: vscode.Uri, to: vscode.Uri, options?: { overwrite?: boolean, ignoreIfExists?: boolean }): void {
+	renameFile(from: vscode.Uri, to: vscode.Uri, options?: { overwrite?: boolean, ignoreIfExists?: boolean; }): void {
 		this._edits.push({ _type: 1, from, to, options });
 	}
 
-	createFile(uri: vscode.Uri, options?: { overwrite?: boolean, ignoreIfExists?: boolean }): void {
+	createFile(uri: vscode.Uri, options?: { overwrite?: boolean, ignoreIfExists?: boolean; }): void {
 		this._edits.push({ _type: 1, from: undefined, to: uri, options });
 	}
 
-	deleteFile(uri: vscode.Uri, options?: { recursive?: boolean, ignoreIfNotExists?: boolean }): void {
+	deleteFile(uri: vscode.Uri, options?: { recursive?: boolean, ignoreIfNotExists?: boolean; }): void {
 		this._edits.push({ _type: 1, from: uri, to: undefined, options });
 	}
 
@@ -1142,6 +1142,10 @@ export class SelectionRange {
 }
 
 export class CallHierarchyItem {
+
+	_sessionId: string;
+	_itemId: string;
+
 	kind: SymbolKind;
 	name: string;
 	detail?: string;
@@ -1496,7 +1500,7 @@ export class Color {
 	}
 }
 
-export type IColorFormat = string | { opaque: string, transparent: string };
+export type IColorFormat = string | { opaque: string, transparent: string; };
 
 @es5ClassCompat
 export class ColorInformation {
@@ -2051,13 +2055,13 @@ export class TreeItem {
 
 	label?: string | vscode.TreeItemLabel;
 	resourceUri?: URI;
-	iconPath?: string | URI | { light: string | URI; dark: string | URI };
+	iconPath?: string | URI | { light: string | URI; dark: string | URI; };
 	command?: vscode.Command;
 	contextValue?: string;
 	tooltip?: string;
 
-	constructor(label: string | vscode.TreeItemLabel, collapsibleState?: vscode.TreeItemCollapsibleState)
-	constructor(resourceUri: URI, collapsibleState?: vscode.TreeItemCollapsibleState)
+	constructor(label: string | vscode.TreeItemLabel, collapsibleState?: vscode.TreeItemCollapsibleState);
+	constructor(resourceUri: URI, collapsibleState?: vscode.TreeItemCollapsibleState);
 	constructor(arg1: string | vscode.TreeItemLabel | URI, public collapsibleState: vscode.TreeItemCollapsibleState = TreeItemCollapsibleState.None) {
 		if (URI.isUri(arg1)) {
 			this.resourceUri = arg1;
diff --git a/src/vs/workbench/contrib/callHierarchy/browser/callHierarchy.ts b/src/vs/workbench/contrib/callHierarchy/browser/callHierarchy.ts
index 745780da5ac151a04bb74f52c92702f8281065e5..cad37346668acccf3f3c9f3d0678a70540bcb969 100644
--- a/src/vs/workbench/contrib/callHierarchy/browser/callHierarchy.ts
+++ b/src/vs/workbench/contrib/callHierarchy/browser/callHierarchy.ts
@@ -9,10 +9,14 @@ import { ITextModel } from 'vs/editor/common/model';
 import { CancellationToken } from 'vs/base/common/cancellation';
 import { LanguageFeatureRegistry } from 'vs/editor/common/modes/languageFeatureRegistry';
 import { URI } from 'vs/base/common/uri';
-import { IPosition } from 'vs/editor/common/core/position';
+import { IPosition, Position } from 'vs/editor/common/core/position';
 import { isNonEmptyArray } from 'vs/base/common/arrays';
 import { onUnexpectedExternalError } from 'vs/base/common/errors';
-import { IDisposable } from 'vs/base/common/lifecycle';
+import { IDisposable, dispose } from 'vs/base/common/lifecycle';
+import { CommandsRegistry } from 'vs/platform/commands/common/commands';
+import { assertType } from 'vs/base/common/types';
+import { IModelService } from 'vs/editor/common/services/modelService';
+import { ITextModelService } from 'vs/editor/common/services/resolverService';
 
 export const enum CallHierarchyDirection {
 	CallsTo = 1,
@@ -20,7 +24,8 @@ export const enum CallHierarchyDirection {
 }
 
 export interface CallHierarchyItem {
-	id: string;
+	_sessionId: string;
+	_itemId: string;
 	kind: SymbolKind;
 	name: string;
 	detail?: string;
@@ -87,10 +92,11 @@ export class CallHierarchyModel {
 		if (!session) {
 			return undefined;
 		}
-		return new CallHierarchyModel(provider, session.root, new RefCountedDisposabled(session));
+		return new CallHierarchyModel(session.root._sessionId, provider, session.root, new RefCountedDisposabled(session));
 	}
 
 	private constructor(
+		readonly id: string,
 		readonly provider: CallHierarchyProvider,
 		readonly root: CallHierarchyItem,
 		readonly ref: RefCountedDisposabled,
@@ -104,7 +110,7 @@ export class CallHierarchyModel {
 		const that = this;
 		return new class extends CallHierarchyModel {
 			constructor() {
-				super(that.provider, item, that.ref.acquire());
+				super(that.id, that.provider, item, that.ref.acquire());
 			}
 		};
 	}
@@ -134,3 +140,71 @@ export class CallHierarchyModel {
 	}
 }
 
+// --- API command support
+
+const _models = new Map<string, CallHierarchyModel>();
+
+CommandsRegistry.registerCommand('_executePrepareCallHierarchy', async (accessor, ...args) => {
+	const [resource, position] = args;
+	assertType(URI.isUri(resource));
+	assertType(Position.isIPosition(position));
+
+	const modelService = accessor.get(IModelService);
+	let textModel = modelService.getModel(resource);
+	let textModelReference: IDisposable | undefined;
+	if (!textModel) {
+		const textModelService = accessor.get(ITextModelService);
+		const result = await textModelService.createModelReference(resource);
+		textModel = result.object.textEditorModel;
+		textModelReference = result;
+	}
+
+	try {
+		const model = await CallHierarchyModel.create(textModel, position, CancellationToken.None);
+		if (!model) {
+			return undefined;
+		}
+		//
+		_models.set(model.id, model);
+		_models.forEach((value, key, map) => {
+			if (map.size > 10) {
+				value.dispose();
+				_models.delete(key);
+			}
+		});
+		return model.root;
+
+	} finally {
+		dispose(textModelReference);
+	}
+});
+
+function isCallHierarchyItemDto(obj: any): obj is CallHierarchyItem {
+	return true;
+}
+
+CommandsRegistry.registerCommand('_executeProvideIncomingCalls', async (_accessor, ...args) => {
+	const [item] = args;
+	assertType(isCallHierarchyItemDto(item));
+
+	// find model
+	const model = _models.get(item._sessionId);
+	if (!model) {
+		return undefined;
+	}
+
+	return model.resolveIncomingCalls(item, CancellationToken.None);
+});
+
+CommandsRegistry.registerCommand('_executeProvideOutgoingCalls', async (_accessor, ...args) => {
+	const [item] = args;
+	assertType(isCallHierarchyItemDto(item));
+
+	// find model
+	const model = _models.get(item._sessionId);
+	if (!model) {
+		return undefined;
+	}
+
+	return model.resolveOutgoingCalls(item, CancellationToken.None);
+});
diff --git a/src/vs/workbench/contrib/extensions/browser/extensionsDependencyChecker.ts b/src/vs/workbench/contrib/extensions/browser/extensionsDependencyChecker.ts
index 07006b77f263b9fcbdf2e6d9eefebdb567cd9b6e..206a53472e1fd0eb76b965614f75905251aa34c0 100644
--- a/src/vs/workbench/contrib/extensions/browser/extensionsDependencyChecker.ts
+++ b/src/vs/workbench/contrib/extensions/browser/extensionsDependencyChecker.ts
@@ -26,10 +26,10 @@ export class ExtensionDependencyChecker extends Disposable implements IWorkbench
 		@IHostService private readonly hostService: IHostService
 	) {
 		super();
-		CommandsRegistry.registerCommand('workbench.extensions.installMissingDepenencies', () => this.installMissingDependencies());
+		CommandsRegistry.registerCommand('workbench.extensions.installMissingDependencies', () => this.installMissingDependencies());
 		MenuRegistry.appendMenuItem(MenuId.CommandPalette, {
 			command: {
-				id: 'workbench.extensions.installMissingDepenencies',
+				id: 'workbench.extensions.installMissingDependencies',
 				category: localize('extensions', "Extensions"),
 				title: localize('auto install missing deps', "Install Missing Dependencies")
 			}
diff --git a/src/vs/workbench/contrib/markers/browser/markersPanelActions.ts b/src/vs/workbench/contrib/markers/browser/markersPanelActions.ts
index ec0dd5602d484f70cf6cdf19e8c8b6320880b356..28a84bbb3f362f07dfc159d863feeb730635e445 100644
--- a/src/vs/workbench/contrib/markers/browser/markersPanelActions.ts
+++ b/src/vs/workbench/contrib/markers/browser/markersPanelActions.ts
@@ -119,20 +119,6 @@ export class MarkersFilterAction extends Action {
 		}
 	}
 
-	focus(): void {
-		this._onFocus.fire();
-	}
-
-	layout(width: number): void {
-		if (width > 600) {
-			this.class = 'markers-panel-action-filter grow';
-		} else if (width < 400) {
-			this.class = 'markers-panel-action-filter small';
-		} else {
-			this.class = 'markers-panel-action-filter';
-		}
-	}
-
 	private _showWarnings: boolean = true;
 	get showWarnings(): boolean {
 		return this._showWarnings;
@@ -165,6 +151,20 @@ export class MarkersFilterAction extends Action {
 			this._onDidChange.fire(<IMarkersFilterActionChangeEvent>{ showInfos: true });
 		}
 	}
+
+	focus(): void {
+		this._onFocus.fire();
+	}
+
+	layout(width: number): void {
+		if (width > 600) {
+			this.class = 'markers-panel-action-filter grow';
+		} else if (width < 400) {
+			this.class = 'markers-panel-action-filter small';
+		} else {
+			this.class = 'markers-panel-action-filter';
+		}
+	}
 }
 
 export interface IMarkerFilterController {
diff --git a/src/vs/workbench/test/electron-browser/api/extHostApiCommands.test.ts b/src/vs/workbench/test/electron-browser/api/extHostApiCommands.test.ts
index 1f9dd15dda5ca58b1cd668a763a9ab3c6bfea55f..20bb18053aeb5dafe52acdbe1b26fdd95b03b6d8 100644
--- a/src/vs/workbench/test/electron-browser/api/extHostApiCommands.test.ts
+++ b/src/vs/workbench/test/electron-browser/api/extHostApiCommands.test.ts
@@ -67,13 +67,13 @@ suite('ExtHostLanguageFeatureCommands', function () {
 			rpcProtocol = new TestRPCProtocol();
 			instantiationService.stub(ICommandService, {
 				_serviceBrand: undefined,
-				executeCommand(id: string, args: any): any {
+				executeCommand(id: string, ...args: any): any {
 					const command = CommandsRegistry.getCommands().get(id);
 					if (!command) {
 						return Promise.reject(new Error(id + ' NOT known'));
 					}
 					const { handler } = command;
-					return Promise.resolve(instantiationService.invokeFunction(handler, args));
+					return Promise.resolve(instantiationService.invokeFunction(handler, ...args));
 				}
 			});
 			instantiationService.stub(IMarkerService, new MarkerService());
@@ -856,4 +856,46 @@ suite('ExtHostLanguageFeatureCommands', function () {
 		assert.equal(value.length, 1);
 		assert.ok(value[0].parent);
 	});
+
+	// --- call hierarcht
+
+	test('CallHierarchy, back and forth', async function () {
+
+		disposables.push(extHost.registerCallHierarchyProvider(nullExtensionDescription, defaultSelector, new class implements vscode.CallHierarchyProvider {
+
+			prepareCallHierarchy(document: vscode.TextDocument, position: vscode.Position, ): vscode.ProviderResult<vscode.CallHierarchyItem> {
+				return new types.CallHierarchyItem(types.SymbolKind.Constant, 'ROOT', 'ROOT', document.uri, new types.Range(0, 0, 0, 0), new types.Range(0, 0, 0, 0));
+			}
+
+			provideCallHierarchyIncomingCalls(item: vscode.CallHierarchyItem, token: vscode.CancellationToken): vscode.ProviderResult<vscode.CallHierarchyIncomingCall[]> {
+
+				return [new types.CallHierarchyIncomingCall(
+					new types.CallHierarchyItem(types.SymbolKind.Constant, 'INCOMING', 'INCOMING', item.uri, new types.Range(0, 0, 0, 0), new types.Range(0, 0, 0, 0)),
+					[new types.Range(0, 0, 0, 0)]
+				)];
+			}
+
+			provideCallHierarchyOutgoingCalls(item: vscode.CallHierarchyItem, token: vscode.CancellationToken): vscode.ProviderResult<vscode.CallHierarchyOutgoingCall[]> {
+				return [new types.CallHierarchyOutgoingCall(
+					new types.CallHierarchyItem(types.SymbolKind.Constant, 'OUTGOING', 'OUTGOING', item.uri, new types.Range(0, 0, 0, 0), new types.Range(0, 0, 0, 0)),
+					[new types.Range(0, 0, 0, 0)]
+				)];
+			}
+		}));
+
+		await rpcProtocol.sync();
+
+		const root = await commands.executeCommand<vscode.CallHierarchyItem>('vscode.prepareCallHierarchy', model.uri, new types.Position(0, 0));
+
+		assert.ok(root);
+		assert.equal(root.name, 'ROOT');
+
+		const incoming = await commands.executeCommand<vscode.CallHierarchyIncomingCall[]>('vscode.provideIncomingCalls', root);
+		assert.equal(incoming.length, 1);
+		assert.equal(incoming[0].from.name, 'INCOMING');
+
+		const outgoing = await commands.executeCommand<vscode.CallHierarchyOutgoingCall[]>('vscode.provideOutgoingCalls', root);
+		assert.equal(outgoing.length, 1);
+		assert.equal(outgoing[0].to.name, 'OUTGOING');
+	});
 });
diff --git a/yarn.lock b/yarn.lock
index 49346cb3369d75d509bbe28cd6a3ca55ab47f06a..c965f033387acbadb4be6e1cdf1638225bf9f54a 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -195,6 +195,20 @@
   resolved "https://registry.yarnpkg.com/@types/winreg/-/winreg-1.2.30.tgz#91d6710e536d345b9c9b017c574cf6a8da64c518"
   integrity sha1-kdZxDlNtNFucmwF8V0z2qNpkxRg=
 
+"@types/yauzl@^2.9.1":
+  version "2.9.1"
+  resolved "https://registry.yarnpkg.com/@types/yauzl/-/yauzl-2.9.1.tgz#d10f69f9f522eef3cf98e30afb684a1e1ec923af"
+  integrity sha512-A1b8SU4D10uoPjwb0lnHmmu8wZhR9d+9o2PKBQT2jU5YPTKsxac6M2qGAdY7VcL+dHHhARVUDmeg0rOrcd9EjA==
+  dependencies:
+    "@types/node" "*"
+
+"@types/yazl@^2.4.2":
+  version "2.4.2"
+  resolved "https://registry.yarnpkg.com/@types/yazl/-/yazl-2.4.2.tgz#d5f8a4752261badbf1a36e8b49e042dc18ec84bc"
+  integrity sha512-T+9JH8O2guEjXNxqmybzQ92mJUh2oCwDDMSSimZSe1P+pceZiFROZLYmcbqkzV5EUwz6VwcKXCO2S2yUpra6XQ==
+  dependencies:
+    "@types/node" "*"
+
 "@webassemblyjs/ast@1.5.13":
   version "1.5.13"
   resolved "https://registry.yarnpkg.com/@webassemblyjs/ast/-/ast-1.5.13.tgz#81155a570bd5803a30ec31436bc2c9c0ede38f25"