[*] darn GTK4 apps don't follow dark theme

Fresh install of Ubuntu Unity , smooth transition, just few fixes, alas some darn GTK4 apps - eg the half-baked file-roller - don't give an F about the dark theme I have (yaru-dark), they also don't obey anymore the  ' dconf write /org/gnome/desktop/interface/color-scheme "'prefer-dark'" ' that works nicely with GTK3 apps.. (FFS really) , took a while to find the solution, put this 

export GTK_THEME=Yaru:dark

into your .profile

Update

Same crap on Fedora (F42) Gnome ! This time fixed by adding : 

export GTK_THEME=HighContrastInverse 

on my aliases file under the  $HOME/.bashrc.d directory
HighContrastInverse a bit more 'compatible' with the HighContrast on Accessibility -if you like that.
btw you can use something else eg GTK_THEME=Adwaita:dark . still some apps may have broken interfaces because of this, eg style and accent colour are not working anymore (effing mess there ... )