Bug 191005 PDF preview hangs up with attached xtab.[1102]
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/layout/pdf/PDFLineAreaLM.java
{
					child.setPosition( child.getX( ), spacing + child.getY( ) );
				}
				else if ( CSSConstants.CSS_MIDDLE_VALUE.equalsIgnoreCase( vAlign ) 
						|| CSSConstants.CSS_BASELINE_VALUE.equalsIgnoreCase( vAlign ))
				{
					child.setPosition( child.getX( ), spacing/2 + child.getY( ) );
				}
				else
				{
					int lineHeight = ( (PDFBlockStackingLM) parent ).getLineHeight( );
					if(lineHeight>0)
					{
						
						child.setPosition( child.getX( ), spacing/2 + child.getY( ) );
					}
				}
			}
		}
	}
	public boolean isEmptyLine( )
	{
		return isRootEmpty( );
	}
	
	private boolean needLineBreak(IContent content)
	{
		int specWidth = 0;
		int avaWidth = getCurrentMaxContentWidth( );
		int calWidth = getDimensionValue( content.getWidth( ) );