Add icon to activity bar (loaded separately than stock Viewlets)

src/vs/workbench/browser/parts/activitybar/activitybarPart.ts

@@ -51,6 +51,15 @@ export class ActivitybarPart extends Part implements IActivityService {
 
 		// Deactivate viewlet action on close
 		this.toUnbind.push(this.viewletService.onDidViewletClose(viewlet => this.onCompositeClosed(viewlet)));
+
+		// Update activity bar on registering an external viewlet
+		this.toUnbind.push(
+			(<ViewletRegistry>Registry.as(ViewletExtensions.Viewlets)).onDidViewletRegister(viewletDescriptor => this.onViewletRegistryUpdated(viewletDescriptor))
+		);
+	}
+
+	private onViewletRegistryUpdated(viewletDescriptor: ViewletDescriptor) {
+		this.viewletSwitcherBar.push(this.toAction(viewletDescriptor), { label: true, icon: true });
 	}
 
 	private onActiveCompositeChanged(composite: IComposite): void {

src/vs/workbench/browser/viewlet.ts

@@ -7,6 +7,7 @@ import nls = require('vs/nls');
 import { TPromise } from 'vs/base/common/winjs.base';
 import DOM = require('vs/base/browser/dom');
 import errors = require('vs/base/common/errors');
+import Event, { Emitter } from 'vs/base/common/event';
 import { Registry } from 'vs/platform/platform';
 import { Dimension, Builder, $ } from 'vs/base/browser/builder';
 import { IAction, IActionRunner, Action } from 'vs/base/common/actions';
@@ -164,12 +165,16 @@ export const Extensions = {
 
 export class ViewletRegistry extends CompositeRegistry<Viewlet> {
 	private defaultViewletId: string;
+	private _onDidViewletRegister = new Emitter<ViewletDescriptor>();
+
+	public get onDidViewletRegister() { return this._onDidViewletRegister.event; }
 
 	/**
 	 * Registers a viewlet to the platform.
 	 */
 	public registerViewlet(descriptor: ViewletDescriptor): void {
 		super.registerComposite(descriptor);
+		this._onDidViewletRegister.fire(descriptor);
 	}
 
 	/**

src/vs/workbench/parts/explorers/browser/treeExplorerViewlet.ts

-import 'vs/css!./media/customViewlet';
-
 import { TPromise } from 'vs/base/common/winjs.base';
 import { Builder, Dimension } from 'vs/base/browser/builder';
 import { SplitView, Orientation } from 'vs/base/browser/ui/splitview/splitview';
@@ -12,7 +10,7 @@ import { IInstantiationService } from 'vs/platform/instantiation/common/instanti
 
 import { TreeView } from 'vs/workbench/parts/explorers/browser/views/treeView';
 
-export const CUSTOM_VIEWLET_ID_ROOT = 'workbench.view.customViewlet.';
+export const CUSTOM_VIEWLET_ID_ROOT = 'workbench.view.treeExplorerViewlet.';
 
 export class TreeExplorerViewlet extends Viewlet {
 	private static _idCounter = 1;