Regular popups are mutually exclusive; only one can be open at a time. A child popup can
coexist with its parent. As long as the parent is open, so is the child. The child can be
closed without closing the parent popup, but closing the parent popup will close the child.
Spawn a new child popup using OverlayIO.
Regular popups are mutually exclusive; only one can be open at a time. A child popup can coexist with its parent. As long as the parent is open, so is the child. The child can be closed without closing the parent popup, but closing the parent popup will close the child.