What was expected?:
That once play mode has been activated, collab actions cannot be invoked or have no effect, including restore, until Play Mode has ended.

What actually happened?:
While play mode did block collab from taking any actions, you can still click the restore button immediately after the play mode button and it will result in a stuck progress bar, either as an infinite spinner in the collab toolbar button or as a modal dialog, usually appearing over the play preview window unless you have done layout rearrangement to avoid it. The restore gets unstuck and back to normal once play mode is exited from.

Steps to reproduce:
1) Have a somewhat large project that compiles to gain some delay between pressing the play mode button and when the play preview actually becomes ready.
2) Make some commits into the project to have some commits to go back to.
3) Click "go back to" on a previous commit besides the latest in the collab history window so you have outstanding changes.
4) Click the play mode button.
5) Immediately click the restore button for the latest commit in the collab history window.
6) Observe stuck progress behavior.

Discovered on the 2017.2.0f1 RC1 build.