In order to define a contextual action for seismic histogram windows, you need to put your Python script in your Python directory under a directory called Contextual_Histogram_Seismic_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 seismic histogram window:
This script will set the clipping range of the window to the smallest amplitude range among the histogram layers contained within it.
This script is attached to the bottom of this article.
The result after the script executes should look something like the following.