Bug 198594 XLS Emitter: Decimal value exported as String instead of Number
engine/org.eclipse.birt.report.engine.emitter.prototype.excel/src/org/eclipse/birt/report/engine/emitter/excel/ExcelWriter.java
writer.openTag( "Interior" );
			writer.attribute( "ss:Color", bgColor );
			writer.attribute( "ss:Pattern", "Solid" );
			writer.closeTag( "Interior" );
		}
	}
	private boolean isValid( String value )
	{
		return StyleConstant.NULL != value;
	}
	private void declareStyle( StyleEntry style, int id )
	{
		writer.openTag( "Style" );
		writer.attribute( "ss:ID", id );
		String horizontalAlign = style.getProperty( StyleConstant.H_ALIGN_PROP );
		String verticalAlign = style.getProperty( StyleConstant.V_ALIGN_PROP );
		writeAlignment( horizontalAlign, verticalAlign );
		writer.openTag( "Borders" );
		String bottomColor = style
				.getProperty( StyleConstant.BORDER_BOTTOM_COLOR_PROP );
		String bottomLineStyle = style
				.getProperty( StyleConstant.BORDER_BOTTOM_STYLE_PROP );
		String bottomWeight = style
				.getProperty( StyleConstant.BORDER_BOTTOM_WIDTH_PROP );
		writeBorder( "Bottom", bottomLineStyle, bottomWeight, bottomColor );
		String topColor = style
				.getProperty( StyleConstant.BORDER_TOP_COLOR_PROP );
		String topLineStyle = style
				.getProperty( StyleConstant.BORDER_TOP_STYLE_PROP );
		String topWeight = style