Meu tema é Ambiance e adicionei
style "scrollbar" {
bg[NORMAL] = shade (0.9, @selected_bg_color)
bg[SELECTED] = shade (0.7, @selected_bg_color)
bg[ACTIVE] = shade (0.7, @selected_bg_color)
bg[PRELIGHT] = shade (0.7, @selected_bg_color)
GtkScrollbar::trough-border = 2
engine "murrine" {
roundness = 8
border_shades = {1.0, 1.0}
contrast = 0.0
}
}
em ~ / .theme / copy_of_the_Ambiance_theme / gtk-2.0 / gtkrc depois de ajustar os tons e funcionou.