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.

If you would like to build the HTML documentation, pass DOCS=true
to the build script. This introduces dependencies on gi-docgen and
python-toml.

NOTE: Version 4.4.x is the end of the line for Slackware 15.0, as newer
versions of this library require newer versions of glib2 and gtk4.