Bug 193886 NPE is thrown when preview external CSS style in ppt[1205]
engine/org.eclipse.birt.report.engine.emitter.ppt/src/org/eclipse/birt/report/engine/emitter/ppt/PPTRender.java
if ( null != dbl )
		{
			for ( Iterator it = dbl.iterator( ); it.hasNext( ); )
			{
				BorderInfo bi = (BorderInfo) it.next( );
				int outerBorderWidth = bi.borderWidth / 4;
				int innerBorderWidth = bi.borderWidth / 4;
				switch ( bi.borderType )
				{
					case BorderInfo.TOP_BORDER :
						drawLine( layoutPointX2PPT( bi.startX ),
								layoutPointY2PPT( bi.startY
										- bi.borderWidth
										/ 2
										+ outerBorderWidth
										/ 2 ),
								layoutPointX2PPT( bi.endX ),
								layoutPointY2PPT( bi.endY
										- bi.borderWidth
										/ 2
										+ outerBorderWidth
										/ 2 ),
								pptMeasure( outerBorderWidth ),
								bi.borderColor,
								"solid" ); 
						drawLine( layoutPointX2PPT( bi.startX
								+ 3
								* borders[BorderInfo.LEFT_BORDER].borderWidth
								/ 4 ),
								layoutPointY2PPT( bi.startY