_popup_win = null;

function popUp(p_page, p_width,  p_height, p_win) {
 var left_pos = (screen.width) ? ((screen.width - p_width) / 2) : 0;
 var top_pos = (screen.height) ? ((screen.height - p_height) / 2) : 0;
 
 var _popup_win = new Window(p_win, p_page, p_width, p_height, left_pos, top_pos);
 _popup_win.features["scrollbars"] = 1;
 
 _popup_win.open();
 var w_ref = _popup_win.getRef(); // reference to the window
 w_ref.focus();
}