TextBuffer.addOnBeginUserAction

Emitted at the beginning of a single user-visible operation on a GtkTextBuffer.

See also: [method@Gtk.TextBuffer.begin_user_action], [method@Gtk.TextBuffer.insert_interactive], [method@Gtk.TextBuffer.insert_range_interactive], [method@Gtk.TextBuffer.delete_interactive], [method@Gtk.TextBuffer.backspace], [method@Gtk.TextBuffer.delete_selection].