* <li> set shapeId for the container descriptor and background
* </p>
*/
public void onCreate(){
//initialize drawing group id
EscherDggRecord dgg = getSlideShow().getDocumentRecord().getPPDrawingGroup().getEscherDggRecord();
EscherContainerRecord dgContainer = (EscherContainerRecord)getSheetContainer().getPPDrawing().getEscherRecords()[0];
EscherDgRecord dg = (EscherDgRecord) Shape.getEscherChild(dgContainer, EscherDgRecord.RECORD_ID);
int dgId = dgg.getMaxDrawingGroupId() + 1;
dg.setOptions((short)(dgId << 4));
dgg.setDrawingsSaved(dgg.getDrawingsSaved() + 1);
dgg.setMaxDrawingGroupId(dgId);
for (Iterator it = dgContainer.getChildContainers().iterator(); it.hasNext(); ) {
EscherContainerRecord c = (EscherContainerRecord)it.next();
EscherSpRecord spr = null;
switch(c.getRecordId()){