xDetails.utextvpDynamic <- function(x, theta) {
    h <- unit(1, "npc") + unit(.2, "lines")
    grobX(rectGrob(height=h, y=1, just="top",
                   vp=paste0(x$name, ".vp")), theta)
}

yDetails.utextvpDynamic <- function(x, theta) {
    h <- unit(1, "npc") + unit(.2, "lines")
    grobY(rectGrob(height=h, y=1, just="top",
                   vp=paste0(x$name, ".vp")), theta)
}