Bug 122854 There is redundant columns in "available columns" list in "export data" dialog.
Description: There is redundant columns in "available columns" list in "export data" dialog. Steps to reproduce: 1. Preview attached design in web viewer. 2. Select the table and click on "export" button. 3. There is a "detail" column name in "available columns" list which is not data set column.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/ir/Report.java
* @param index
	 *            style index
	 * @return style
	 */
	public IStyle getStyle( int index )
	{
		assert ( index >= 0 && index < styles.size( ) );
		return (IStyle) this.styles.get( index );
	}
	/**
	 * add a style definition into the report.
	 * 
	 * @param style
	 *            style definition.
	 */
	public void addStyle( String name, CSSStyleDeclaration style )
	{
		assert ( style != null );
		this.styles.add( style );
		this.styleTable.put( name, style );
	}
	public Set getStyleSet( )
	{
		return styleTable.entrySet( );
	}
	/**
	 * Finds the style in the report.
	 * 
	 * @param name
	 *            The name of the style.