src/vs/workbench/contrib/output/browser/outputView.ts/SwitchOutputActionViewItem/constructor
class SwitchOutputActionViewItem:	constructor(
		action: IAction,
		@IOutputService private readonly outputService: IOutputService,
		@IThemeService private readonly themeService: IThemeService,
		@IContextViewService contextViewService: IContextViewService
	) {
		super(null, action, [], 0, contextViewService, { ariaLabel: nls.localize('outputChannels', "Output Channels"), optionsAsChildren: true });

		const outputChannelRegistry = Registry.as<IOutputChannelRegistry>(Extensions.OutputChannels);
		this._register(outputChannelRegistry.onDidRegisterChannel(() => this.updateOptions()));
		this._register(outputChannelRegistry.onDidRemoveChannel(() => this.updateOptions()));
		this._register(this.outputService.onActiveOutputChannel(() => this.updateOptions()));
		this._register(attachSelectBoxStyler(this.selectBox, themeService));

		this.updateOptions();
	}