Bug 313297 XML data set fail in chart data preview
chart/org.eclipse.birt.chart.ui/src/org/eclipse/birt/chart/ui/swt/CustomPreviewTable.java
cnvCells.redraw( );
	}
	public Color getColumnColor( int iIndex )
	{
		if ( iIndex > cnvCells.colors.length )
		{
			throw new IllegalArgumentException( Messages.getString( "CustomPreviewTable.Exception.InvalidColumnIndexSpecified" ) ); 
		}
		return cnvCells.colors[iIndex];
	}
	public void clearContents( )
	{
		btnHeaders.clear( );
		columnWidths.clear( );
		fHeadings.clear( );
		iVScroll = 0;
		iLastProcessedHorizontalScrollPosition = 0;
		iLastProcessedVerticalScrollPosition = 0;
		iHiddenWidth = 0;
		Control[] c = this.cmpHeaders.getChildren( );
		for ( int i = 0; i < c.length; i++ )
		{
			c[i].dispose( );
		}
		cnvCells.clearContents( );
	}
	public void setHeaderAlignment( int iAlignment )
	{
		this.iHeaderAlignment = iAlignment;
		for ( int i = 0; i < btnHeaders.size( ); i++ )