Interactive debugging

Figure 18. The inspector

The inspector

GTK includes an interactive debugger, called the GTK Inspector, which lets you explore the widget tree of any GTK application at runtime, as well as tweak the theme and trigger visual debugging aids. You can easily try out changes at runtime before putting them into the code.

Note that the GTK inspector can only show GTK internals. It can not understand the application-specific logic of a GTK application. Also, the fact that the GTK inspector is running in the application process limits what it can do. It is meant as a complement to full-blown debuggers and system tracing facilities such as DTrace, not as a replacement.

To enable the GTK inspector, you can use the Control-Shift-I or Control-Shift-D keyboard shortcuts, or set the GTK_DEBUG=interactive environment variable.

There are a few more environment variables that can be set to influence how the inspector renders its UI. GTK_INSPECTOR_DISPLAY and GTK_INSPECTOR_RENDERER determine the GDK display and the GSK renderer that the inspector is using.

In some situations, it may be inappropriate to give users access to the GTK inspector. The keyboard shortcuts can be disabled with the enable-inspector-keybinding key in the org.gtk.Settings.Debug GSettings schema.