It is posible to update the login widget so it redirects you ater login
validate : function(response, ioArgs) {
logger.debug(this.id + ".validate");
this.indicator && this.indicator.stop();
dojo.cookie("EXTENDCOOKIE", this.checkboxInput.checked, { expires: 365 });
var i18nmap = this.i18nmap;
var span = this.messageNode;
switch(ioArgs.xhr.status) {
case 200 :
mendix.widget.hideTooltip();
mx.login();
if(this.redirectURLmf !== "" ) //have a MF that return the theme index file liek: mytheme-index.html
this.redirectURL(this.redirectURLmf);
in following link you will find the updated version of the widget: Widget
Lets take a look. In the index-default.html is the line
<div dojoType="mxui.widget.ThemeSwitch" themes="Default;Basic;Dutch;Dark"
label="Pick your theme:"></div>
Which displays the themeswitcher. Normally the mx stuff is in the runtime. On your local machine goto C:/program files/Mendix/4.5.2./runtime/mxclientsystem.
Use a find tool and look for ThemeSwitch. Seems to be in mxui/widget/ThemeSwitch.js. But not readable. Format the file with a tool like notepad++. The only thing what happens is:
window.location.replace("index-" + this.selectNode.value + ".html");
You can do that even in html/Javascript snippet widget.