Last Friday, I finally got the newest release of Xfce, Xfce 4.12. However, after logging in, I saw a horizontal line running on the lower part of my screen from one side to another.
At first I thought (and dreaded) that it’s a driver issue, or that my display is broken, but the line only appeared when I use Xfce; it doesn’t appear when I switch to Unity or use Windows.
I googled and found no issues that resemble mine, but I got the idea to take a screenshot of my screen and see if the line appeared on the result. It was.
A closer look made me notice that the line appeared on top of Cairo Dock, and hovering over the file browser applet made similar lines appeared around it.
I finally found the fix: open Window Manager Tweaks and untick the ‘Show shadows under dock windows’ checkbox on the Compositor tab. It would remove shadows from under docks and deskbars.
As a comparison, here’s my desktop with and without shadows under dock windows:
I also have another issue; the Appearance settings won’t start. Running it from the terminal (xfce4-appearance-settings) suggested that the problem was buffer overflow. Haven’t found anything similar to this.