Boxplot with theme_void() in 4.0.0 gets a background

[daattali]

I discovered the bug in daattali/ggExtra#182 and was sure it was my fault! But looks like it might not be? @thomasp85 I wasn't crazy :)

Run the following code in ggplot 3.5.1 and 4.0.0:

ggplot(mtcars, aes(x = factor(cyl), y = mpg)) +
    geom_boxplot(alpha = 0.5) + theme_void()

These are the plots you get:

[teunbrand]

Thanks for the report! The new theme defaults populate boxplots with a completely transparent black fill in theme_void(). By setting alpha = 0.5, you're getting rid of the 'completely' part of that setting, which shows up as gray. I don't think it'd make sense for us to revert any of the ggplot2 4.0.0 changes or make special-case exceptions for this use case.

[daattali]

Only theme_void() seems to do that, most other themes don't. This is on purpose?

[teunbrand]

Yes, theme void has a transparent paper of whatever the ink colour is. By default, ink is black, so paper becomes transparent black (#00000000), whereas most other themes have simply paper = "white".

[teunbrand]

In any case, I'm not inclined into rolling back the change that causes this. If you want semi-transparent white fill, you can simply set fill = alpha("white", 0.5) instead of alpha = 0.5.