src/vs/workbench/contrib/welcome/page/browser/welcomePage.ts/WelcomePageContribution/openWelcome
class WelcomePageContribution:	private async openWelcome() {
		const startupEditorSetting = this.configurationService.getValue(configurationKey);
		const startupEditorTypeID = (startupEditorSetting === 'welcomePage' || startupEditorSetting === 'welcomePageInEmptyWorkbench') ? gettingStartedInputTypeId : welcomeInputTypeId;
		const editor = this.editorService.activeEditor;

		// Ensure that the welcome editor won't get opened more than once
		if (editor?.typeId === startupEditorTypeID || this.editorService.editors.some(e => e.typeId === startupEditorTypeID)) {
			return;
		}
		const options: IEditorOptions = editor ? { pinned: false, index: 0 } : { pinned: false };
		if (startupEditorTypeID === gettingStartedInputTypeId) {
			this.editorService.openEditor(this.instantiationService.createInstance(GettingStartedInput, {}), options);
		} else {
			this.instantiationService.createInstance(WelcomePage).openEditor(options);
		}
	}