Description:

Parasite is a debugging and development tool that runs inside your GTK+
application's process. It can inspect your application, giving you detailed
information on your UI, such as the hierarchy, X window IDs, widget
properties, and more. You can modify properties on the fly in order to
experiment with the look of your UI.

Parasite includes an embedded Python shell that lets you write new code that
directly interacts with your application's UI, regardless of the language the
application is written in. Create new dialogs, attach temporary signal
handlers to buttons, test out new logic, and gather additional debug
information.