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
{
				return ERROR_MSG_CANNOT_BE_NULL;
			}
		}
		if ( canBeBlank( ) )
		{
			if ( StringUtil.isBlank( value ) )
			{
				return null;
			}
		}
		else
		{
			if ( StringUtil.isBlank( value ) )
			{
				return ERROR_MSG_CANNOT_BE_BLANK;
			}
		}
		try
		{
			getValue( value );
		}
		catch ( BirtException e )
		{
			return ERROR_MSG_MISMATCH_DATA_TYPE;
		}
		return null;
	}
	private boolean isEqual( String value1, String value2 )
	{