make ~/.vim/vimrc as the fellow:

set background=light
colo morning


Then open some text, and move the cursor up and down, you will see it draws 
 thin lines between each lines you ever moved over before!

But it has no problem when using dark color theme! Maybe, the extra lines are
mixed into the dark background, I think!

Is it a bug introduced when building vim on openSUSE, or just a bug originated
in vim?

Is there anyway to prevent this problem when using light color schemes?