gtkparasite
GTK+ debugging tool similar to Firebug
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. If you've used Firebug, it's sort of like that, but for GTK+ applications.
There is no official package available for openSUSE Leap 15.6Distributions
SUSE SLE-15-SP1
Unsupported distributions
The following distributions are not officially supported. Use these packages at your own risk.