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 ( refresh )
			{
				refreshValueTable( );
			}
		}
	}
	private boolean canBeBlank( )
	{
		boolean canBeBlank = false;
		if ( PARAM_CONTROL_LIST.equals( getSelectedControlType( ) )
				|| DesignChoiceConstants.PARAM_CONTROL_TEXT_BOX.equals( getSelectedControlType( ) ) )
		{
			if ( dirtyProperties.containsKey( CHECKBOX_ALLOW_BLANK ) )
			{
				canBeBlank = ( (Boolean) dirtyProperties.get( CHECKBOX_ALLOW_BLANK ) ).booleanValue( );
			}
			else
			{
				canBeBlank = inputParameter.allowBlank( );
			}
		}
		return canBeBlank;
	}
	private boolean canBeNull( )
	{
		boolean canBeNull = false;
		if ( PARAM_CONTROL_LIST.equals( getSelectedControlType( ) )
				|| DesignChoiceConstants.PARAM_CONTROL_TEXT_BOX.equals( getSelectedControlType( ) ) )
		{
			if ( dirtyProperties.containsKey( CHECKBOX_ALLOW_NULL ) )