Hi - I have a few applets on my panel, such as weather, the notification area, cpu / net load, etc. All of the icons and the background are just a black box. The icons are there - I can mouse over them and click on them, but all I see is a black bar on my panel where the icons should be. I also have a couple applets that are not blacked out: the XFCE menu, the Audio Mixer, and Orage (clock). I'm running 4.14 on Gentoo. I looked around for similar bugs and noticed some solutions suggested editting ~/.config/gtk-3.0/gtk.css, which I don't have. Not sure if that's important or not. I typically use the xfce-dawn theme. I tried changing to others, such as Adwaita (since it has a gtk-3.0 directory in /usr/share/themes, in case that matters). But no luck with other themes.
A report for this issue was opened just recently -> Bug 16106.
Thanks! I commented on that one. *** This bug has been marked as a duplicate of bug 16106 ***