beginIrreversibleAction
Denotes the beginning of an action that may not be undone.
This will cause any previous operations in the undo/redo queue to be cleared.
This should be paired with a call to method@Gtk.TextBuffer.end_irreversible_action after the irreversible action has completed.
You may nest calls to gtk_text_buffer_begin_irreversible_action() and gtk_text_buffer_end_irreversible_action() pairs.