annotation_custom: Annotation: Custom grob.

# Dummy plot df <- data.frame(x = 1:10, y = 1:10) base <- ggplot(df, aes(x, y)) +  geom_blank() +  theme_bw()  # Full panel annotation base + annotation_custom(  grob = grid::roundrectGrob(),  xmin = -Inf, xmax = Inf, ymin = -Inf, ymax = Inf )  # Inset plot df2 <- data.frame(x = 1 , y = 1) g <- ggplotGrob(ggplot(df2, aes(x, y)) +  geom_point() +  theme(plot.background = element_rect(colour = "black"))) base +  annotation_custom(grob = g, xmin = 1, xmax = 10, ymin = 8, ymax = 10)