When the plank dock is active on my computer, it causes an unsightly line that pierces through the desktop, as shown here: Problems with Plank dock
This line does not just go through the wallpaper, but also pierces through all of the windows in the desktop, as well.
I honestly do not know what caused this. I have been using Plank since I started using linux late last year and never had this issue.
A few things that I have done that might be responsible are installing and subsequently uninstalling Google Chrome (this coincided with several other weird errors, such as odd font rendering in Firefox) and unplugging my computer from my TV without safely disconnecting it.
I have already uninstalled and re-installed Plank, but it comes back exactly the same. What should I do? I am using Xubuntu 14.04 and xfce 4.12. I also have Gnome 3 installed and switch back and forth between xfce and Gnome very frequently (in case that helps)
Edit: I have tried both Docky and Cairo dock and they both have the same problem as plank. They all cause the line through the desktop.