Avoid re-rendering the tree when icon is clicked

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

@@ -34,6 +34,10 @@ export class ActivitybarPart extends Part implements IActivityService {
 	private viewletsToggleStatus: { [viewletId: string]: boolean; };
 	private registeredViewlets: string[];
 
+	// Since the internal viewlet can't get the external viewlet's id upon initialization,
+	// internal viewlet initializes with id like 'workbench.view.customTreeExplorerViewlet.1'.
+	// This maps the internal viewlet id to externalId like 'workbench.view.customTreeExplorerViewlet.myTree'
+	private internalViewletIdMap: { [externalViewletId: string]: string; };
 	private externalViewletIdToOpen: string;
 
 	private VIEWLETS_TOGGLE_STATUS = 'workbench.activityBar.viewletsToggleStatus';
@@ -56,6 +60,8 @@ export class ActivitybarPart extends Part implements IActivityService {
 
 		this.registeredViewlets = [];
 
+		this.internalViewletIdMap = {};
+
 		this.registerListeners();
 	}
 
@@ -117,6 +123,10 @@ export class ActivitybarPart extends Part implements IActivityService {
 		return this.externalViewletIdToOpen;
 	}
 
+	setInternalViewletId(externalViewletId: string, internalViewletId: string): void {
+		this.internalViewletIdMap[externalViewletId] = internalViewletId;
+	}
+
 	public showActivity(compositeId: string, badge: IBadge, clazz?: string): void {
 		const action = this.compositeIdToActions[compositeId];
 		if (action) {
@@ -174,7 +184,7 @@ export class ActivitybarPart extends Part implements IActivityService {
 	}
 
 	private toAction(composite: ViewletDescriptor): ActivityAction {
-		const action = this.instantiationService.createInstance(ViewletActivityAction, composite.id + '.activity-bar-action', composite);
+		const action = this.instantiationService.createInstance(ViewletActivityAction, composite.id + '.activity-bar-action', composite, this.internalViewletIdMap);
 		action.onOpenViewlet((viewletId) => {
 			this.externalViewletIdToOpen = viewletId;
 		});
@@ -212,7 +222,9 @@ class ViewletActivityAction extends ActivityAction {
 	get onOpenViewlet(): Event<string> { return this._onOpenViewlet.event; };
 
 	constructor(
-		id: string, private viewlet: ViewletDescriptor,
+		id: string,
+		private viewlet: ViewletDescriptor,
+		private internalViewletIdMap: { [externalViewletId: string]: string; },
 		@IViewletService private viewletService: IViewletService,
 		@IPartService private partService: IPartService
 	) {
@@ -236,7 +248,12 @@ class ViewletActivityAction extends ActivityAction {
 			this.partService.setSideBarHidden(true);
 		} else {
 			this._onOpenViewlet.fire(this.viewlet.id);
-			this.viewletService.openViewlet(this.viewlet.id, true).done(null, errors.onUnexpectedError);
+			// If the viewlet is external and has been initialized, find the internal viewlet id for opening
+			if (this.viewlet.isExternal && this.internalViewletIdMap[this.viewlet.id]) {
+				this.viewletService.openViewlet(this.internalViewletIdMap[this.viewlet.id], true).done(null, errors.onUnexpectedError);
+			} else {
+				this.viewletService.openViewlet(this.viewlet.id, true).done(null, errors.onUnexpectedError);
+			}
 			this.activate();
 		}
 

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

@@ -38,6 +38,7 @@ export class TreeExplorerViewlet extends Viewlet {
 
 		this.externalViewletId = this.activityService.getExternalViewletIdToOpen();
 		this.treeNodeProviderId = this.getTreeProviderName(this.externalViewletId);
+		this.activityService.setInternalViewletId(this.externalViewletId, VIEWLET_ID_ROOT + TreeExplorerViewlet._idCounter);
 
 		TreeExplorerViewlet._idCounter++;
 	}

src/vs/workbench/parts/explorers/browser/views/treeExplorerView.ts

@@ -90,13 +90,11 @@ export class TreeExplorerView extends CollapsibleViewletView {
 	}
 
 	create(): TPromise<void> {
-		return TPromise.as(null);
+		return this.updateInput();
 	}
 
 	setVisible(visible: boolean): TPromise<void> {
-		return super.setVisible(visible).then(() => {
-			this.updateInput().done();
-		});
+		return super.setVisible(visible);
 	}
 
 	private updateInput(): TPromise<void> {

src/vs/workbench/services/activity/common/activityService.ts

@@ -85,4 +85,10 @@ export interface IActivityService {
 	 * Get the external viewlet id to open
 	 */
 	getExternalViewletIdToOpen(): string;
+
+	/**
+	 * Tell activitybar the internal viewlet id corresponding to the external viewlet id
+	 * once the viewlet is initialized
+	 */
+	setInternalViewletId(externalViewletId: string, internalViewletId: string): void;
 }
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