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
String value = null;
			if ( COLUMN_VALUE.equals( property ) )
			{
				value = choice.getValue( );
			}
			else if ( COLUMN_DISPLAY_TEXT.equals( property ) )
			{
				value = choice.getLabel( );
			}
			if ( value == null )
			{
				value = ""; 
			}
			return value;
		}
		public void modify( Object element, String property, Object value )
		{
			if ( element instanceof Item )
			{
				element = ( (Item) element ).getData( );
			}
			SelectionChoice choice = ( (SelectionChoice) element );