I've the same effect aftwer upgrading to 12.04 Beta1 2 days ago. I'm using GNOME Classic (no effects). I can clearly see that it's theme problem - when I change it to any other menus change.
For comparison I've installed GnomishDark theme from http://gnome-look.org/content/show.php/GnomishDark?content=147290 and it looks 100% OK (dark menus). So maybe Ambiance developers should take a look at GnomishDark theme to see how it should be done.
I've the same effect aftwer upgrading to 12.04 Beta1 2 days ago. I'm using GNOME Classic (no effects). I can clearly see that it's theme problem - when I change it to any other menus change.
For comparison I've installed GnomishDark theme from http:// gnome-look. org/content/ show.php/ GnomishDark? content= 147290 and it looks 100% OK (dark menus). So maybe Ambiance developers should take a look at GnomishDark theme to see how it should be done.