XHTML Strict and target _blank

This topic is quite a challange because on one side I want my websites "strict" valid. On the other hand, sometimes it's important (at least clients say so) to open links in a new window, so I did a little research (and there are a lot of informations out there to this problem)

What are the solutions for being valid and in the same time opening links in a new window?

1. I tried it with CSS: (I know, I know... CSS is for styling only, not for behavior.. I'm searching solutions right now)
Theoretically it can be done with CSS3. According to this page the code should look like this:

a {
    target-name: new;
    target-new: tab;
}

But none of the browsers responded to it so this solution is precluded.



2. Javascript:
Here we have quite interesting solutions.

Manually open a new window with "window.open(URL)":

Inline mode:

<a href="http://thinkrement.blogger.com" onclick="window.open(this.href); return false;">Read Thinkrement!</a>

This works, however it's not so elegant and it's better to keep the HTML and Javascript seperate.

So, let's improve it a bit:

HTML:

<a href="http://thinkrement.blogger.com" rel="popup">Read Thinkrement!</a>

Javascript:

window.onload = function() {
    var links = document.getElementsByTagName('a');
    for (var i=0;i < links.length;i++) {
        if (links[i].rel == 'popup') {
            links[i].onclick = function() {
                window.open(this.href);
                return false;
            };
        }
    }
};

or with jQuery:

$('a[rel="popup"]').click(function() {
    window.open(jQuery(this).attr("href"));
    return false;
});

The constrained method:

With Javascript it's similar to the previous "window.open" method with the difference, that instead of "window.open" we use:

window.onload = function() {
    var links = document.getElementsByTagName('a');
    for (var i=0;i < links.length;i++) {
        if (links[i].rel == 'popup') {
            links[i].target="_blank";
        }
    }
};

This is quite simple, however this solution is not supported by IE and Chrome.

With jQuery it a bit easier (only 1 line):

$('a[rel="popup"]').attr("target", "_blank");

3. HTML:
- Use a Transitional Doctype
- Have some "target" errors on your site
- or put it out of your mind that you want to use the target attribute. It is said that for usability reasons it's better to let users decide whether they want a new window (tab) or not.