By sorting the windows in the current workspace first, we ensure that
when using alt+tab to switch windows, we will pick a window on the
active workspace as the default focused window for the application if
the application has at least one window on the current workspace (that
is, if it is on the left of the app switcher separator).
This makes the behaviour of alt+tab more predictable for the user, as
an user will expect alt+tab to switch to the window he/she can see right
now rather than the one on the workspace he just left (presumably to do
something else on the workspace he's currently on).
https://bugzilla.gnome.org/show_bug.cgi?id=590563
4798ad5107