src/vs/platform/driver/electron-main/driver.ts/Driver/getWindowIds
class Driver:	async getWindowIds(): Promise<number[]> {
		const windowIds = this.windowsMainService.getWindows()
			.map(window => window.id)
			.filter(windowId => this.registeredWindowIds.has(windowId) && !this.reloadingWindowIds.has(windowId));

		return windowIds;
	}