The present disclosure describes techniques for designing effects. A first window comprising a first copy of a first scene may be created. The first scene comprises a first visual effect. A second window comprising a second copy of the first scene may be created. The first window and the second window are configured to enable testing and comparison of different versions of the first visual effect in the first scene at an approximately same time. The first copy of the first scene in the first window may be modified based on a first change to at least one attribute of the first visual effect in the first copy of the first scene. The second copy of the first scene in the second window may be modified based on a second change to at least one attribute of the first visual effect in the second copy of the first scene.