In order to define a contextual action for combined windows, you need to put your Python script in your Python directory under a directory called Contextual_Combined_Window.
Go to Tools->Options->Environment->Python Scripts (or Tools->Options->Python->Scripts in INTViewer 5.2) and click "Refresh from Disk". Your script should be listed automatically.
You will now be able to execute this script from the contextual menu of the combined window:
This script will remove the 3D windows from the combined window, and put them in a new combined window.
This script is attached to the bottom of this article.
The result after the script executes should look something like the following.