GtkEditable::insert_text
void insert_text(int 
position, string 
text);
 
    
     Inserts text at the given position.
    
    Example 56. Inserting text at the beginning
$text = $editable->insert_text(0, 'begin');
      | 
 
    Example 57. Inserting text at the end
$text = $editable->insert_text(
    strlen($editable->get_chars(0, -1)),
    'end'
);
      |