gconftool-2 -s -t string /apps/notify-osd/multihead_mode focus-follow
or
gsettings
set com.canonical.notify-osd multihead-mode focus-follow
gconftool-2 -s -t string /apps/notify-osd/multihead_mode focus-follow
or
gsettings
set com.canonical.notify-osd multihead-mode focus-follow