Key glyph regression from ggplot2 v4.0.0

[mitchelloharawild]

This is an upstream issue to be fixed in ggplot2, but I'm also reporting it here for visibility if others encounter similar problems.

In ggplot2 v4.0.0, there is a bug in draw_key_rect() where fill isn't used.

library(ggdist)
library(ggplot2)
data.frame(
  t = 1:10,
  y = distributional::dist_normal(1:10, 1)
) |> 
  ggplot(aes(x = t, ydist = y)) +
  stat_lineribbon(aes(fill = after_stat(level)), .width = c(.5, .8, .95)) +
  scale_fill_brewer()

^{Created on 2025-09-12 with reprex v2.1.1}

draw_key_rect isn't actually used in ggplot2's geoms anywhere, they instead use draw_key_polygon which should be better tested.

A quick fix (for users and for ggdist) is to replace usage of draw_key_rect with draw_key_polygon:

library(ggdist)
library(ggplot2)
data.frame(
  t = 1:10,
  y = distributional::dist_normal(1:10, 1)
) |> 
  ggplot(aes(x = t, ydist = y)) +
  stat_lineribbon(aes(fill = after_stat(level)), .width = c(.5, .8, .95), key_glyph = draw_key_polygon) +
  scale_fill_brewer()

^{Created on 2025-09-12 with reprex v2.1.1}

A PR fixing this upstream in ggplot2 has been submitted here: tidyverse/ggplot2#6609

[teunbrand]

A quick fix (for users and for ggdist) is to replace usage of draw_key_rect with draw_key_polygon:

I'd recommend this regardless

[mjskay]

Thanks! Should be fixed on master now (thanks @mitchelloharawild for pinpointing the issue, made it easy to fix). Should be pushing to CRAN sometime this week.