The dimpled damsel of Bollywood, Preity Zinta, has effortlessly gone from being a star of hyped-up, big-budget crowd-pullers to an actress to take on the challenge of lending her name and talent to films rooted in the real world and its myriad issues. Deepa Mehta`s "Heaven on Earth," in which Zinta plays a battered Punjabi housewife in Canada who is a victim of domestic violence has just had its world premiere in Toronto. Banish the thought, she asserts "Popular Hindi cinema is my bread and butt