If a (modal) ice:confirmationPanel within a modal ice:panelPopup is used, the confirmationPanel will not be centered; instead it seems to be centered relative to the panelPopups upper left edge.
This seems to be caused by the inline style of the panelPopup. It says position: absolute. Because it is rendered as inline style, I don't know how to change it to position: fixed which seems to solve the problem.
Additional information:
In my case it would be no solution to put the confirmation panel outside the panelPopup, because the confirmationPanel is part of a Facelets-Component (ui:composition). Whenever this component is used inside a panelPopup, this problem arises.
Any solution proposals?
I ended up creating my own popup component, which uses position: fixed divs instead of iframes - works perfect!