gir1.2-gtksource-300 binary package in Ubuntu Oracular armhf

 libgedit-gtksourceview is a library that extends GtkTextView, the
 standard GTK widget for multiline text editing. This library 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.
 .
 This package contains GObject introspection information.

Source package