Bug 166315 Combo box doesn't allow blank when set string type in parameter editor
Combo box doesn't allow blank when set string type in parameter editor Steps to reproduce: 1.New a parameter, display type is Combo Box 2.Select data type as String Expected result: "Allow blank values" is enable. Actual result: "Allow blank values" is gray and can't be checked.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/ParameterDialog.java
if ( dialog.open( ) == Dialog.OK )
			{
				choice.setValue( convertToStandardFormat( choice.getValue( ) ) );
				choiceList.add( choice );
				return true;
			}
			return false;
		}
		public boolean removeItem( Object[] elements )
		{
			for ( int i = 0; i < elements.length; i++ )
			{
				if ( isDefaultChoice( (SelectionChoice) elements[i] ) )
				{
					changeDefaultValue( null );
				}
				choiceList.remove( elements[i] );
			}
			return true;
		}
	};
	private Text listLimit;
	/**
	 * Create a new parameter dialog with given title under the active shell
	 * 
	 * @param title
	 *            the title of the dialog
	 */
	public ParameterDialog( String title )
	{