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
* @return [number][other]
	 */
	public static String[] splitString( String value )
	{
		String[] spt = new String[2];
		if ( value != null )
		{
			for ( int i = value.length( ); i > 0; i-- )
			{
				if ( isValidNumber( value.substring( 0, i ) ) )
				{
					spt[0] = value.substring( 0, i );
					spt[1] = value.substring( i, value.length( ) );
					break;
				}
			}
			if ( spt[0] == null && spt[1] == null )
			{
				spt[1] = value;
			}
		}
		return spt;
	}
	/**
	 * If given value if null, return an empty string, or return itself.
	 * 
	 * @param value
	 *            a String value.
	 * @return non-null value.
	 */