function App() {
  const { isChatSettingOpen, setChatSettingOpen } = useUIOpenControlState();
  
  function toggleChatSettingOpen() {
    setChatSettingOpen(!isChatSettingOpen);
  }
  
  return (
     <UIKitProvider>
        <div style={{ maxWidth: '300px' }}>
          <ConversationList />
        </div>
        <Chat
          PlaceholderEmpty={null}
          style={{
            display: 'flex',
            flexDirection: 'row',
            flex: 1,
            maxHeight: '100vh',
          }}
        >
          <div style={{
            display: 'flex',
            flexDirection: 'column',
            flex: 1,
            minWidth: '0',
          }}
          >
            <button onClick={toggleChatSetting}>toggle</button>
            <MessageList />
            <MessageInput />
          </div>
          {isChatSettingOpen && <ChatSetting style={{ width: '350px' }} />}
        </Chat>
      </UIKitProvider>
  );
}