* @param font the font to apply to the appended text or <code>null</code> if no formatting is required
*/
public void append(String text, XSSFFont font){
if(st.sizeOfRArray() == 0 && st.isSetT()) {
//convert <t>string</t> into a text run: <r><t>string</t></r>
CTRElt lt = st.addNewR();
lt.setT(st.getT());
preserveSpaces(lt.xgetT());
st.unsetT();
}
CTRElt lt = st.addNewR();
lt.setT(text);
preserveSpaces(lt.xgetT());
CTRPrElt pr = lt.addNewRPr();
if(font != null) setRunAttributes(font.getCTFont(), pr);
}