Center popup window on the Screen with Javascript

Javascript Window open() Method opens a popup window. How to center this window on the screen?

A solution could be the following function: CenterWindow

<script>
        /**
         * Opens window screen centered.
         * @param windowWidth the window width in pixels (integer)
         * @param windowHeight the window height in pixels (integer)
         * @param windowOuterHeight the window outer height in pixels (integer)
         * @param url the url to open
         * @param wname the name of the window
         * @param features the features except width and height (status, toolbar, location, menubar, directories, resizable, scrollbars)
         */
        function CenterWindow(windowWidth, windowHeight, windowOuterHeight, url, wname, features) {
                var centerLeft = parseInt((window.screen.availWidth - windowWidth) / 2);
                var centerTop = parseInt(((window.screen.availHeight - windowHeight) / 2) - windowOuterHeight);

                var misc_features;
                if (features) {
                        misc_features = ', ' + features;
                }
                else {
                        misc_features = ', status=no, location=no, scrollbars=yes, resizable=yes';
                }
                var windowFeatures = 'width=' + windowWidth + ',height=' + windowHeight + ',left=' + centerLeft + ',top=' + centerTop + misc_features;
                var win = window.open(url, wname, windowFeatures);
                win.focus();
                return win;
        }
</script>

Usage

Here is an example

<a href="javascript:void(0)"
   onclick="CenterWindow(1000,800,50,'http://www.pontikis.net','demo_win');">Click here</a>

Your comments are welcome!