Christofe your answer lies in JavaScript and in Dreamweaver's excellent replace function.
Add the following code to the <head> area of all pages where you need to open something in a new window:
<script type="text/javascript">
function OpenNewWindow(bigurl, width, height)
{
var newWindow = window.open("", "pictureViewer",
"location=no, directories=no, fullscreen=no, " +
"menubar=no, status=no, toolbar=no, width=" +
width + ", height=" + height + ", scrollbars=no");
newWindow.document.writeln("<html>");
newWindow.document.writeln("<body style='margin: 0 0 0 0;'>");
newWindow.document.writeln("<a href='javascript:window.close();'>");
newWindow.document.writeln("<img src='" + bigurl +
"' alt='Click to close' id='bigImage'/>");
newWindow.document.writeln("</a>");
newWindow.document.writeln("</body></html>");
newWindow.document.close();
}
</script>
Now, anything you need to open in a new window, you can use the following JavaScript function:
<a href="#" onclick="OpenNewWindow('images/bigpicture.jpg', 500, 500); return true;">
<img src="images/smallpicture.jpg" alt="Click..."/>
</a>
You can format it for any size, I have it set for 500x500 pixels squre.
You can also change the newWindow.document.writeln statements to include everything from text, headers, footers and so on.
I would also mention that it's probably time for a redesign of your website anyway. Your drop-down menus cover other menus. And I would create a master page and make that a Dreamweaver Template, that way your "embiggerizor" JavaScript code can be put into all pages by default.
