Idea about editing a keyframe on a time-locked 3d viewport while 2nd viewport shows animation realtime

Hi, it would be great to have a double-feature where on two separated 3d viewports, we could get one of them to lock to a specific frame while the 2nd viewport would display the animation. This way, a keyframe could be edited interactively while visualising the result in real time. It would require the first viewport to ignore playback and lock to a desired frame. It could synchronize with the last selected keyframe in the Timeline editor.