It would be great if we could control the position of popup. Such have it open right next to where the user clicks (or centered over or above that). Could do with relative x,y coordinates to the mouse click too.

There a quite a few instances I would use this. One use case is want a very small module (one or two fields) to add a record to a list. Better UI experience to not have to adjust where you are looking/working, and then go back to the previous spot on the screen.

Another is to allow the editing of a record, but requiring verification before making the change. A popup with a password field and final submit button.