Open http://www.wikipedia.org/, initial focus position is:
Firefox 3.6 and Opera 12.14 focus is search box at bottom of the screen, the seems to be the most normal;
Firefox 4.0 to latest versions focus is automatically focus search box at center of the screen;
Google Chrome 25 is automatically focus search box at top of the screen;
IE9, initial focus not in the search box.

This is a browser compatibility problems?

Version: unspecified
Severity: minor
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=1864