code: public MultiChangeBuilder<PS, SEG, S> insertText(int paragraphIndex, int columnPosition, String text) {
          int index = area.getAbsolutePosition(paragraphIndex, columnPosition);
          return replaceText(index, index, text);
      }
docs: Inserts the given text at the position returned from
  {@code getAbsolutePosition(paragraphIndex, columnPosition)}.
  
  <p><b>Caution:</b> see {@link StyledDocument#getAbsolutePosition(int, int)} to know how the column index argument
  can affect the returned position.</p>
  
  @param text The text to insert