Add shortcut UI control for existing a scene

[jacobsimionato]

Currently, if you want to browse different scenes, the UI flow is:

1. Open scene
2. Open environment controls
3. Click back
4. Choose new scene

Moving between different scenes is a common flow, so it'd be great to eliminate step2. I know we want to avoid obscuring the app layout, but it seems worthwhile for this. Though this won't be as important if #17 is fixed, seeing as it won't be a problem for large screens any more.