I upgraded from 15.6 to 16.0. I’m using LXDE, and it seems the lxpanel’s tray is broken: the background around icons is not redrawn (when switching bluetooth on and off, for example).
This might be related: https://github.com/lxde/lxpanel/issues/117
Unfortunately, the only solution mentioned there is to compile lxpanel yourself, which I wasn’t able to do (configure failed for libfm-gtk and I wasn’t able to install the devel version without breaking many other packages). The problem doesn’t happen in xfce4-panel, but it’s missing some of the plugins I’d like to use.