GTK_THEME. If set, makes GTK+ use the named theme instead of the theme that is specified by the gtk-theme-name setting. This is intended mainly for easy debugging of theme issues. It is also possible to specify a theme variant to load, by appending the variant name with a colon, like this: GTK_THEME=Adwaita:dark.
I'd love it if I could change gnvim's window border using
GTK_THEME=Adwaita:dark gnvim
, but this doesn't seem to have any effect.From the Running GTK+ Applications page:
Thanks for the great app!