Closing the search window with accel key also closes child windows

Steps to reproduce:

1. Perform a search.
2. Choose a result item, open containing folder.
3. Switch back to the search window.
4. Press <ctrl>-<w> to close the window.

Expected Results: Only the search window is closed.

Actual Results: The search window is closed. The window opened from the search window is closed (that one with the containing folder).

Note: This does not happen if you use the close window button.