The new theming system means that the look and feel of plots can be dramatically changed - even just by using base ggplot2 convenience functions theme_grey(), theme_classic() etc. 🎉

Currently, paper and ink are arguments in these functions that let users change the background and forground colors - including layer colors! (amazing!)

However, the user cannot change the accent color (blue in geom_smooth for example) as theme_grey and friends are currently written. This feels a bit strange to me, because you can affect the colors (as well as size) for all grobs from the convience theme_* functions -- except if the grob happens to be defined by accent. But the geom_smooth's blue (and a handful of other grobs') is untouchable unless you learn or find some more involved syntax.

Just knowing geom_smooth's popularity and use in a lot of ggplot2 education to demonstrate building up plot layers, I wonder if making accent available in theme functions could be considered. 🙏