Rules of Heyawake

The grid is subdivided into multiple rectangular regions by thick lines. Shade some cells such that:

1. No two shaded cells are orthogonally adjacent.
2. Each numbered region correctly states the number of shaded cells within it.
3. All unshaded cells are connected.
4. No unbroken orthogonal line of unshaded cells straddles two region boundaries.

Below is an example and its answer.