fix working of setGroupHeaders if grid inside of hidden div (inactive jQuery UI Tab, for example)
fix working of setGroupHeaders if grid inside of hidden div (inactive jQuery UI Tab, for example)

Thanks @davgino (https://github.com/davgino) for the bug report! See [the issue](https://github.com/free-jqgrid/jqGrid/issues/230).

javapark/jqgrid