This file serves as an example of a working dropdown menu in MATLAB to replace the deprecated uisplittools

sample_dropdown_with_down_arrow.m

% Create a figure and add a toolbar to it
fig = figure('Toolbar', 'none', 'MenuBar', 'none', 'Name', 'Custom Toolbar Dropdown', 'WindowButtonDownFcn', @(src, event)hideContextMenu(src));
tb = uitoolbar(fig);
% Load the icon (e.g. greenarrowicon)
icon = fullfile(matlabroot,'/toolbox/matlab/icons/greenarrowicon.gif');
[cdata,map] = imread(icon);
% Convert white pixels into a transparent background
map(map(:, 1) + map(:, 2) + map(:, 3) == 3) = NaN;
% Convert into 3D RGB-space
cdataRedo = ind2rgb(cdata,map);

% Create a blank image of the same size as the original image with all values set to NaN
arrowImg = NaN(size(cdataRedo));

% Draw a black triangle in the middle of the image
arrowHeight = size(cdataRedo, 1)/4;  % Height of the arrow is 1/4 the height of the original image
arrowWidth = size(cdataRedo, 2);  % Width of the arrow is the same as the width of the original image
startRow = size(cdataRedo, 1)/2 - arrowHeight/2;  % Start drawing the triangle from the middle of the image
for i = 1:arrowHeight
    arrowImg(startRow+arrowHeight-i, arrowWidth/2-i+1:arrowWidth/2+i-1) = 0;  % Draw each row of the triangle
end

% Append the arrow image to the right of the original image
cdataRedo = horzcat(cdataRedo, arrowImg);

% Create a push tool in the toolbar
pt = uipushtool(tb,'cdata',cdataRedo,'TooltipString','Dropdown Menu', 'Separator', 'on');
% Set the callback for the click on image-icon
pt.ClickedCallback = @(src, event)dropdownClicked(src, event, fig);



function dropdownClicked(~, ~, fig, flag)
    % Define items for the dropdown
    items = {'Movement Function', 'Transformation Function', 'Experiment Code'};
    % Create a context menu (acts as dropdown)
    cm = uicontextmenu(fig);

    % Populate the context menu with items
    for i = 1:length(items)
        % Different callback function can be made for each option of
        % the context menu. Here, selction option is printed
        uimenu(cm, 'Label', items{i}, 'Callback', @(s,e)disp(['Selected Option: ', items{i}]));
    end

    % Sample position of the context-menu
    dropdownPos = [15, 420];
    cm.Position = dropdownPos;
    % Make the context menu visible
    cm.Visible = 'on';
end

function hideContextMenu(src)
    % Hide the context menu by setting the figure's UIContextMenu to none
    src.UIContextMenu = [];