In the code below, how do I set background color and transparency for`tm_compass()`as I can do for map title?

```
library(tmap)
library(dismo)

ny.map <- gmap(x = "New York", zoom = 13, type = "satellite")

print(tm_shape(shp = ny.map) +
      tm_raster() +
      tm_compass(position = c("right", "top"),
                 type = "4star",
                 show.labels = 2) +
      tm_layout(title = "New York",
                title.bg.color = "white",
                title.bg.alpha = 0.5))

```

[![enter image description here](https://i.stack.imgur.com/jPycn.jpg)](https://i.stack.imgur.com/jPycn.jpg) 
Thanks