Hi Jorge,
Not seeing the top bar with the minimize/maximize buttons was a permanent change that was made to the designer in 6.4. You should see a ruler on top and left though, something I didn't spot on your image.
If you are using a "with sources" installation make sure you have all the necessary references (see here) and also make sure you have cleared all your cache and rereferenced the Gizmox dll's (see here).
Palli