A text widget implementing syntax highlighting and other features (source files)
gtksourceview_source-4.8.4-1-source
GtkSourceView is a GNOME library that extends GtkTextView, the standard GTK widget for multiline text editing. GtkSourceView adds support for syntax highlighting, undo/redo, file loading and saving, search and replace, a completion system, printing, displaying line numbers, and other features typical of a source code editor.