Rated 3 out of 5 stars
Maury, I found a fix for TB 52. The extension is looking for a preference which no longer exists, but you can add it back easily. Open TB's Config Editor and add a new Integer key called "alerts.totalOpenTime". This is the amount of delay (in milliseconds) before the tooltip is shown when you hover over the photo. I've set mine to 1000 (= 1sec).
As for the review, I like the flexibility of image sources this extension allows, but I'm not going to use it. Simply put, it's ugly. Adding a picture to the header is purely an aesthetic change, and I just find the way it's done to be unattractive. Let's call it three stars. Very good functionality but the appearance doesn't suit me.