Bug 139110 GUI enhancement to support create subquery more conveniently.
Description: GUI enhancement to support create subquery more conveniently. Steps to reproduce: Subquery means insert table/list inside another table/list item, and the inner table/list item doesn't has its own dataset binding. In latest build, if you want to creat a subquery structure, you have to use dataSetRow as binding expression for data items in inner table/list item. For example: 1. Insert a list, generate column data binding for it. 2. Add a group for the list. 3. Insert table to list group header which is used to display data rows in list group. Dont' bind table to dataset. 4. Insert a data to table detail row. 5. New a binding column for data, click to Open Expression Builder. The issue is that only "Availabel column bindings" is listed in Category but no "Available Data Sets". So I have to type dataSetRow[".."] by myself to generate correct subquery. For users, maybe they will mistakenly use "Available column bindings" which will generate expression like row._outer[".."] and get wrong result. So it is recommended to add "Available Data Sets" in Expression Builder for such case.
UI/org.eclipse.birt.report.designer.core/src/org/eclipse/birt/report/designer/util/DEUtil.java
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	public static Iterator getStyles( Comparator comparator )
	{
		List styles = SessionHandleAdapter.getInstance( )
				.getReportDesignHandle( )
				.getAllStyles( );
		Object[] stylesArray = styles.toArray( );
		if ( comparator != null )
		{
			Arrays.sort( stylesArray, comparator );
		}
		return Arrays.asList( stylesArray ).iterator( );
	}
	/**
	 * Checks if two strings have same value.
	 * 
	 * @param str1
	 * @param str2
	 * @return
	 */
	public static boolean isSameString( String str1, String str2 )
	{
		if ( str1 == null && str2 == null )
		{
			return true;
		}
		if ( str1 != null && str1.equals( str2 ) )
		{
			return true;
		}