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
|| formatCategroy == DesignChoiceConstants.NUMBER_FORMAT_TYPE_CUSTOM
						|| formatCategroy == DesignChoiceConstants.DATETIEM_FORMAT_TYPE_CUSTOM )
				{
					displayFormat += ": " + formatPattern; 
				}
				if ( type.equals( DesignChoiceConstants.PARAM_TYPE_DATETIME ) )
				{
					previewString = new DateFormatter( formatCategroy != DesignChoiceConstants.DATETIEM_FORMAT_TYPE_CUSTOM ? formatCategroy
							: formatPattern,
							ULocale.getDefault( ) ).format( new Date( ) );
				}
				else if ( type.equals( DesignChoiceConstants.PARAM_TYPE_STRING ) )
				{
					previewString = new StringFormatter( formatCategroy != DesignChoiceConstants.STRING_FORMAT_TYPE_CUSTOM ? formatCategroy
							: formatPattern,
							ULocale.getDefault( ) ).format( Messages.getString( "ParameterDialog.Label.Sample" ) ); 
				}
				else
				{
					previewString = new NumberFormatter( formatCategroy != DesignChoiceConstants.NUMBER_FORMAT_TYPE_CUSTOM ? formatCategroy
							: formatPattern,
							ULocale.getDefault( ) ).format( 123456789.01234 );
				}
			}
		}
		formatField.setText( displayFormat );
		previewLabel.setText( previewString );
		changeFormat.setEnabled( choiceSet != null );
	}
	private boolean containValue( SelectionChoice selectedChoice,