I just upgraded from xubuntu 16.04 to 18.04.1.
Now I can't see some buttons and sliders. Menu configuration option buttons are not visible. Slider for volume control for pulseaudio is not visible. On the whisker menu, I see circles covering the names of categories. Terminal window pull-down menu items have no spaces but they are clickable and selecting items from the pull-down menu work.
Applications seem to work for the most part, but not being able to control the volume and not seeing the categories on the whisker menu are super annoying. I don't know what else may be broken. Can someone point me in the right direction? Is this a matter of destroying/modifying some dot files for configuration? I removed the whisker rc file, but the problem persists.