Swiss cheese immigration

This CBC story seems strange:

Voters in Switzerland have approved a proposal to ban the construction of minarets on mosques, according to early results of a referendum.

Projections based on partial returns show support for the ban rose from only 37 per cent a week ago to 59 per cent in Sunday's voting, paving the way for a constitutional amendment.

The nationalist Swiss People's Party, the largest party in parliament, had pushed for the national vote after labelling the mosque towers as symbols of militant Islam.
Has there been some sort of change to Swiss immigration policy in the last fifteen years? I seem to recall a classmate moving to Switzerland after graduating high school, and she was only able to immigrate because she had partial Swiss ancestry.

So how did all these derka derkas get in?