gtkparasite is great for
gtk+2, but unfortunately it won't work with
Is there any alternative?
If you are looking at all the possibilities that can resolve the problem, I suggest the following link which is about how to port
gtkparasite to GTK3. Although it is a bit technical, the effort is successful.
Yes, there's now an official GNOME tool called
GtkInspector is the built-in interactive debugging support in GTK+. It was added in GTK+ 3.14, based on a copy of the well-estabished gtkparasite. To enable the debugger, either start your app with
GTK_DEBUG=interactivein your environment, or run
gsettings set org.gtk.Settings.Debug enable-inspector-keybinding trueand launch the debugger with the Control-Shift-I or Control-Shift-D keyboard shortcuts.