Multiline Text Editor

Text Widget Overview - Overview of GtkTextBuffer, GtkTextView, and friends
GtkTextIter - Text buffer iterator
GtkTextMark - A position in the buffer preserved across buffer modifications
GtkTextBuffer - Stores attributed text for display in a GtkTextView
GtkTextTag - A tag that can be applied to text in a GtkTextBuffer
GtkTextTagTable - Collection of tags that can be used together
GtkTextView - Widget that displays a GtkTextBuffer