I am using [the new header grouping feature of jqgrid 4.2](http://www.trirand.com/blog/?p=857) which works great except that it left aligns all of the text in the header groups.

How can align the header group text to be center in the cell?

Here is a screenshot to show you how it seems to be working by default: (I want "Books" to be center aligned")

NOTE: the regular column headers ARE center aligned.

![enter image description here](https://i.stack.imgur.com/xEcD0.png)