cross-browser popunder

All browsers nowadays block popup windows and popunders. There are many workarounds for different browsers, and I need a cross-browser solution. I need you to provide a single-file javascript code, which will be included in a webpage like this: var popunder_url="[login to view URL]"; Your script will open a popunder and will load the URL from popunder_url variable inthere. Define: Popunder is a browser window opened under the current webpage while the original webpage still keeps focus. Since automatically opened window is mostly blocked in all browsers, your script should attach appropriate event listeners on click events and open the popunder on first user click rather than on page load, because that way the browsers will let it go through. Several hacks may be needed to properly open the popunder on all browsers, including focus() and blur() manipulation, hidden iframe form submit, and so on. However since the user most likely clicks on a link which he wants to follow (even a link with target=_blank attribute), the user experience must be preserved - when the user clicks the link, the popunder should load under the current webpage and the current webpage must still behave like before: if the link clicked had no target attribute, it should simply load the link in current window. If the link clicked had a target=_blank attribute, a new tab or window must be opened which gets the focus, exactly the same as like if no popunder was opened. The popunder must jump to back in all circumstances and the user must be able continue browsing the very same way like if the popunder was not opened. It is probable that the popunder will flicker for a short while while it is opening, that is acceptable, but then it has to blur to background. It has to work properly in IE, Chrome and Firefox (all latest versions).