Hi,
2. The demo website displays the same regardless of the browser you're using. I don't see why it would be different. Please provide the link and we can check.
3. It's done by HikaShop.
4.
In all the case login should appear whatever chekbox is selected !!
Why is that ? If you turn off the "login" setting above, then it won't display.
And if you have only a guest checkout without registration, you might not want the login to appear. So it's normal that it is optional.
5.
Does the chekbox is really usefull ? why not put all the item in the select box
They are, otherwise, we would have done it differently.
It's stupid to have a registration and a simplified registration activated at the same time. Because that would mean that you would let the customer choose how to register (with or without selecting a password and entering a username). It would be confusing to the customer. So it's one or the other.
And we don't put all the elements in a dropdown because otherwise you could select a mode which wasn't checked in the "registration" setting, and that would be illogical. What should the program do if you select the "registration" mode as default if you didn't select it as one of the modes available to the customer ? So to avoid that illogical case, you can only select among the selected choices in that dropdown.
6.
perhap the behaviour inside chekbox cant be implemented inside the select box .
is it not easier to have only select box wit hchekbox in it instead another chekbox ?.
HTML doesn't allow for that.
You can have HTML in the choices of a dropdown.