GTK+ provides many ways to customize the styles of widgets. Most customization of widget styles is done through style properties and resource (RC) files, which were covered in the Widget Styles section of Chapter 4.
In addition to the information in Chapter 4, this appendix provides a reference to default RC file elements that can be applied to any widget, the Pango Text Markup Language, and
Resource files are introduced in Chapter 4, but this section can be used as a reference of the default styles supported by every widget.
Along with the background, foreground, base, and text color styles, you need to specify a widget state for which many styles will be attributed. States are ...