In order to define a contextual action for FT windows, you need to put your Python script in your Python directory under a directory called Contextual_F_T_Analysis_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 FT window:
This script will iterate over the FT layers in the window, find the smallest and largest trace indexes used by them, and build a seismic histogram between those extremes.
This script is attached to the bottom of this article.
The result after the script executes should look something like the following.