Bug 146796 Error message pop up if display text contain non-digital char when add next item
Description: In decimal type parameter creation,display type is "list box", Error message pop up if "display text" contain non-digital char when add next item. Steps: 1.Create a new decimal parameter 2.Set display type as "list box" 3.Input one item: value:1, display text:test 4.Input another item: Value:2 Actual result: error message pop up: The display text already exists! Expected result: Input item succussfully.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/ParameterDialog.java
if ( string != null
				&& DesignChoiceConstants.PARAM_TYPE_DATETIME.equals( getSelectedDataType( ) ) )
		{
			try
			{
				string = new DateFormatter( STANDARD_DATE_TIME_PATTERN ).format( DataTypeUtil.toDate( string,
						ULocale.US ) );
			}
			catch ( BirtException e )
			{
			}
		}
		return string;
	}
	private String getExpression( String columnName )
	{
		for ( Iterator iter = columnList.iterator( ); iter.hasNext( ); )
		{
			ResultSetColumnHandle cachedColumn = (ResultSetColumnHandle) iter.next( );
			if ( cachedColumn.getColumnName( ).equals( columnName ) )
			{
				return DEUtil.getExpression( cachedColumn );
			}
		}
		return null;
	}
	private String getColumnName( String expression )
	{
		for ( Iterator iter = columnList.iterator( ); iter.hasNext( ); )
		{