Bug 315035 [Automation][Regression]Error happened while merge cells in grid when preview as pdf/ppt/ps
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/nLayout/area/impl/TableLayout.java
return emptyCell;
	}
	/**
	 * Creates dummy cell and updates its delta value.
	 * 
	 * @param upperCell
	 *            the upper cell.
	 * @return the created dummy cell.
	 */
	private DummyCell createDummyCell( CellArea upperCell )
	{
		DummyCell dummyCell = null;
		CellArea refCell = null;
		RowArea lastRow = (RowArea) rows.getCurrent( );
		int lastRowHeight = lastRow.getHeight( );
		int delta = 0;
		if ( upperCell instanceof DummyCell )
		{
			refCell = ( (DummyCell) upperCell ).getCell( );
			dummyCell = new DummyCell( refCell );
			delta = ( (DummyCell) upperCell ).getDelta( ) + lastRowHeight;
			dummyCell.setDelta( delta );
		}
		else
		{
			refCell = upperCell;
			dummyCell = new DummyCell( upperCell );
			dummyCell.setDelta( lastRowHeight );
		}
		dummyCell.setRowSpan( upperCell.getRowSpan( ) - 1 );