You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: panel_options.m
    path of file: ./repos/brainstorm3/toolbox/gui
    
    the code of the file until where you have to start completion: function varargout = panel_options(varargin)
% PANEL_OPTIONS:  Set general Brainstorm configuration.
%
% USAGE:  [bstPanelNew, panelName] = panel_options('CreatePanel')
%                                    panel_optio
    
function ButtonSave_Callback(varargin)
        % Save options
        SaveOptions()
        % Hide panel
        gui_hide(panelName);
    end

%% ===== CANCEL BUTTON =====
    function ButtonCancel_Callback(varargin)
        % Hide panel
        gui_hide(panelName);
    end


%% ===== TEMP DIRECTORY SELECTION =====
    % Callback for '...' button
    function TempDirectory_Callback(varargin)
        % Get the initial path
        initDir = bst_get('BrainstormTmpDir', 1);
        % Open 'Select directory' dialog
        tempDir = uigetdir(initDir, 'Select temporary directory.');
        % If no directory was selected : return without doing anything
        if (isempty(tempDir) || (tempDir(1) == 0))
            return
        end