src/vs/workbench/browser/parts/views/treeView.ts/CustomTreeView/activate
class CustomTreeView:	private activate() {
		if (!this.activated) {
			this.progressService.withProgress({ location: this.id }, () => this.extensionService.activateByEvent(`onView:${this.id}`))
				.then(() => timeout(2000))
				.then(() => {
					this.updateMessage();
				});
			this.activated = true;
		}
	}