Question

I have seen people apply the CSS property zoom: 1; on HTML elements.

Why do they do this, and what bug does it fix?

Answer 1

This provides an internal property known as hasLayout in Internet Explorer versions 7 and lower.

The definitive article on the subject is here: http://www.satzansatz.de/cssd/onhavinglayout.html

A lot of Internet Explorer’s rendering
inconsistencies can be fixed by giving
an element “layout.” In this article,
the authors focus on some aspects of
this complicated matter.

“Layout” is an IE/Win proprietary
concept that determines how elements
draw and bound their content, interact
with and relate to other elements, and
react on and transmit application/user
events.

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For an example of a specific bug that zoom: 1 (and so hasLayout) helps to fix:

Inline block doesn't work in internet explorer 7, 6