This is a special pagetype which can be used as a pagetype for a button. This way you can refresh the content of a grid, after a button is clicked. This can be very usefull to show different results.
Buttons with gridrefresh as pagetype when clicked. The grid will refresh according to the result.
When gridrefresh is used as pagetype for a result, it won't open a new page with a grid or a form, it will refresh the corresponding grid.