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: VBA_initDisplay.m
    path of file: ./repos/VBA-toolbox/core/display
    
    the code of the file until where you have to start completion: function [options] = VBA_initDisplay(options,priors)
% initialize VBA graphical output display
% function [options] = VBA_initDisplay(options,priors)
    
function changeSource(hObject,evt,si)

    % get data stored in the figure
    hPanel = get(hObject,'parent');
    ud = get(hPanel,'userdata');
    
    % update the source index and store back
    ud.currentSource = get(hObject,'Value');
    set(hPanel,'userdata',ud);
    
    % try to update display
    if isfield(ud,'update_plot')
        ud.update_plot();
    end