I have a tiny MCE button but I'd like to make it open a popup (that is a custom php page). How do I go about doing this?

tinymce.create('tinymce.plugins.tinyplugin', {
 
        init : function(ed, url){
            ed.addButton('tinyplugin', {
            title : 'map',
                onclick : function() {
                   // make my pop up window?
                },
                image: url + "/icon.png"
            });
        }
    });

I have a tiny MCE button but I'd like to make it open a modal window(like for the spellcheck). How do I go about doing this?

tinymce.create('tinymce.plugins.tinyplugin', {
 
        init : function(ed, url){
            ed.addButton('tinyplugin', {
            title : 'map',
                onclick : function() {
                   // make my pop up window?
                },
                image: url + "/icon.png"
            });
        }
    });