I've seen several questions about this but they are more than 2 years old so I'm guessing this is solved by now: Is it possible to centre the popup to the middel of the screen when the popup has a custom width? When i have wide popups my popups open in the right side of the screen
Niels van de Sande
I filed a ticket for this recently and it's accepted and scheduled for somewhere in the future..
A blocking popup is automatically centered on the screen, at least in 4.7.1 version. Just define your popup as blocking. Hope that helps.