Add drop down in wordpress tiny mce editor pop up

See here, I think it’s enough for making any kind of TinyMCE Editor button with extended options like dropdown etc

https://www.gavick.com/blog/wordpress-tinymce-custom-buttons

Anyway if we came down to dropdown, checkbox and radio button on Popup, here is a demonstration.

(function () {
tinymce.PluginManager.add('aptmce_btn', function (editor, url) {
    editor.addButton('aptmce_btn', {
        text: 'Add popup',
        icon: false,
        onclick: function () {
            editor.windowManager.open({
                title: 'Enter Your PopUp Contents',
                body: [
                    {
                        type: 'textbox',
                        name: 'textboxName',
                        label: 'Title',
                        value: ''

                    },
                    {
                        type: 'textbox',
                        name: 'multilineName',
                        label: 'Content',
                        value: '',
                        multiline: true,
                        minWidth: 300,
                        minHeight: 100
                    },
                    {
                        type: 'listbox', 
                        name: 'timeformat', 
                        label: 'Time Format', 
                        'values': [
                            {text: 'AM', value: 'am'},
                            {text: 'PM', value: 'pm'}
                        ]
                    },
                    {
                        type: 'checkbox',
                        name: 'blank',
                        label: 'Open link in a new tab'
                    },
                    {
                        type: 'radio',
                        name: 'active',
                        label: 'Active Something'
                    }


                ],
                onsubmit: function (e) {
                    target="";
                    if(e.data.blank === true) {
                        target += 'newtab="on"';
                    }
                    editor.insertContent('[show_popup  title="' + e.data.textboxName + '" content="' + e.data.multilineName + '" timeformat="' + e.data.timeformat + '" something="' + e.data.active + '" ' + target + ' ]');
                  }
               });
           }
       });
   });
})();

Remember One thing, radio type will act like a checkbox because radio button not complete yet, see here https://github.com/tinymce/tinymce/blob/ca0f454b9001b9f20aa26349b25f6d839c1a1146/js/tinymce/skins/lightgray/Radio.less

But if you want to multiple radio button options then you can use listbox (Dropdown) instead multiple radio types.

Hope it helps you.