Simulations in EditorWindow

I'm trying to develop something like the simulations of particles in unity(except it's not for particles, it's for gameobjects), I change the Transforms property of objects in the scene in my EditorWindow( at edit time, not play time, using Time.realTimeSinceStartup), the problem is... I don't know how to change the Transforms of the objects back to it's initial state when the user closes the window/pushes play/clicks on some other component, to be more specific, I don't know where I should put my code to revert the gameobjects' transforms to their initial state.

 

You can use EditorApplication.playmodeStateChanged to get notified when the playmode state changes.