Bug 178519 Problems in multi-rows header
Please see the attachments.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/layout/pdf/PDFTableLM.java
{
				tableWidth = Math.min( specifiedWidth, avaWidth - marginWidth );
				return new TableLayoutInfo(
						handleColummVisibity( columnWidthResolver.resolve(
								tableWidth, avaWidth - marginWidth ) ) );
			}
			else
			{
				tableWidth = Math.min( specifiedWidth, parentMaxWidth
						- marginWidth );
				return new TableLayoutInfo(
						handleColummVisibity( columnWidthResolver.resolve(
								tableWidth, parentMaxWidth - marginWidth ) ) );
			}
		}
	}
	private int[] handleColummVisibity( int[] columns )
	{
		
		int colWidth[] = new int[columnNumber];
		for ( int i = 0; i < columnNumber; i++ )
		{
			IColumn column = tableContent.getColumn( i );
			if ( isColumnHidden( column ) )
			{
				colWidth[i] = 0;
			}
			else
			{
				colWidth[i] = columns[i];