I have a Fancybox which shows me some dialog and a button to click. When i click this button i want to open another fancybox over the existing one.. or on another position o
Unfortunately you cannot have more than a single fancybox at the same time ... it has been designed like that.
You could have another fancybox inside of the existing one though (when open an external page -via iframe- with fancybox in it) ...or you could open that inner fancybox on the parent page, creating the illusion that you have two fancyboxes on the same page. Check here for more
On the other hand, the only lightbox I remember that supports multiple boxes is jQuery Tools Overlay
Open first fancybox in iframe. Then inside that another fancybox can be open.