如何在Xcode IDE中启用垂直分割视图?

I'm diving into iOS development and I'm using Xcode on a multi-monitor setup. Obviously I want to take advantage of the multiple monitors to view and edit multiple panes of source code, but I'm having a hard time figuring out how to enable vertical split views. In other IDEs, it's just an option you click in the "Window" menu. How do I enable vertical split views in Xcode?I'm diving into iOS development and I'm using X