Create and draw shadow text by wrapping a textual expression into a colored
framing.
Usage
stextGrob(
label,
x = grid::unit(0.5, "npc"),
y = grid::unit(0.5, "npc"),
col = "white",
fill = "black",
r = 0.1,
gp = grid::gpar(),
vp = NULL,
name = NULL,
...
)