I am attaching a video. Open any application, switch to some other
application using ALT+TAB and when you come back to it, you shall see
white border around the window.
** Attachment added: "out.ogv"
https://bugs.launchpad.net/ubuntu/+source/gnome-desktop/+bug/1157220/+attachment/3588396/+file
Public bug reported:
After upgrading to Ubuntu 12.10, I started seeing a white border around
my terminal whenever I switch between windows. It starts flickering as I
type in the terminal. The border goes off when I resize it to normal and
then back to full screen or maximize mode. It appears again