While we have the option for script tabs "Move to new Instance", to see script side by side in different windows/instances, we can't easily move tabs/scripts between existing instances (like we can in Notepad++ or any prolific web browser).

As of now, we have to save the script we want to move (if we hadn't already) and open in manually in the desired instance via the File menu. Drag and drop would be so much more convenient.