I’d like to add a button to my page that when pressed opens a pop window (over the current browser window) to another page on my site. I’d like the main browser window to be deactivated (or out of focus) until this popup window’s either been closed or the form has been completed on this page- like a payment window or registration window.
I’m not sure that I need a plugin. I just want to open a link in a window that is in focus over the main window. Is there a way to do that instead of opening in a new tab?
I want it to behave like the top button on the linked paged I provided behaves.
The example you provided is a Pop Up also known as a Modal window. It is not a function of the browser. So you would need to use a plugin or have it coded.