Open Application Page depending on ListSettings

I am using an Application page and want to open it in a modal dialog so I am using the current code:

    var siteUrl = _spPageContextInfo.webServerRelativeUrl;
    var options = {
        url: siteUrl + '/_layouts/MT/Page.aspx?itemid=',
        width: 640,
        height: 480
    };

    SP.UI.ModalDialog.showModalDialog(options);

But the user is able to change the list settings so that dialogs are usually not opened in a popup. This works fine for EditForm and those but not for mine. This still opens in popup. Is there a chance to get the list settings property by javascript, so I am able to decide how to open? Or do I need to customize my Custom Action with two different URLs?