Some standard Xfce themes contain color settings for tooltips: style "tooltips" = "default" { bg[NORMAL] = "#ffffdf" fg[NORMAL] = "#101010" } widget "gtk-tooltips*" style "tooltips" As far as I can tell, these settings are ignored by the theme engine: No matter what is defined in the theme, all tooltips have the normal dialog background and foreground color. In my private theme, I also tried to increase the spacing between the text and the tooltip border: style "tooltips" = "default" { xthickness = 4 ythickness = 4 bg[NORMAL] = @tooltip_bg_color fg[NORMAL] = @tooltip_fg_color } These settings are also ignored: The border is much too close to the text. In the gtk3 Gtk-xfce-engine the tooltip theme definitions work fine.
The name of the tooltip widget might have changed in them past, since I see more themes with this problem. This line doesn't match the tooltips: widget "gtk-tooltips*" style "tooltips" the next both line do match: widget "gtk-tooltip*" style "tooltips" widget "gtk-tooltip" style "tooltips" I'll fix this match in the default themes too.
Changing that line fixes the problem for me.
Fixed for the default themes in commit e9d9e7b