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
public void setColumns( ColumnBindingInfo[] headers )
	{
		clearContents( );
		if ( headers.length == 0 )
		{
			createDummyTable( );
			return;
		}
		isDummy = false;
		int iW = cnvCells.getVisibleTableWidth( ) / headers.length;
		if ( iW < TableCanvas.SCROLL_HORIZONTAL_STEP )
		{
			iW = TableCanvas.SCROLL_HORIZONTAL_STEP;
		}
		for ( int i = 0; i < headers.length; i++ )
		{
			fHeadings.add( headers[i] );
			columnWidths.add( Integer.valueOf( iW ) );