• VSCode Version: 1.17.2
• OS Version: Microsoft Windows [Version 10.0.16299.19]

Steps to Reproduce:

1. Open Workspace Settings
2. Observe how there is no split editor button.

Reproduces without extensions: Yes

I think this is a useful feature to have because you usually want to see how your changing your settings affects your files live. On a widescreen monitor, the settings page doesn't really need to take up the entire screen anyways.

If this feature is wanted, I would like to do the PR.