I'm pretty sure that it is not GWT since: 1. It was released several years before GWT. 2. It has no GWT CSS class names on anything. 3. It does have some wei

I'm pretty sure that it is not GWT since: 1. It was released several years before GWT. 2. It has no GWT CSS class names on anything. 3. It does have some weird IFRAME structures that are unlike what GWT uses. 4. It doesn't have any of the long hexadecimal identifier files that GWT uses to compile to different targets. 5. On the wire, it doesn't look at all like GWT AJAX requests. 6. Isaac Truett <itru...@gmail.com> says it isn't at http://groups.google.com/group/Google-Web-Toolkit/browse_thread/thread/beb685af839718d2/2dd5665b53a6eb11 http://groups.google.com/group/Google-Web-Toolkit/browse_thr... This was in 2007, but I don't believe they threw away a working product to do a rewrite in GWT, which was still not fully mature and is still hard to get just right. And if they did, they'd also have had to make it look like it is not written in that framework in every way I can think to check easily. (EDIT) 7. Since nothing significant is written in GWT, they'd be trumpeting it from the rooftops if GMail was.