With the Script Editor dialog displayed, you can edit the Python code for your script by clicking the Text Editor button. (Be aware that if you’ve already modified the script in the Script Editor dialog, you’ll be prompted to save or discard changes prior to switching to the text editor application.) The editor application designated for script editing will open.
To change the application designated
by Paint Shop Pro for editing Python script code Choose File
> Preferences > File Locations (or click the File
Locations button 
in the Select Script drop-list)
to open the File Locations dialog.
In the File Types list, choose Python Source Editor.
On the right side of the dialog, enter the path for the editor application you wish to use. Click Browse if you need to navigate for the correct path.
About the Script Toolbar Buttons
Using the File > Script Menu Items
Editing Scripts Using Paint Shop Pro