1.6] Hook hookActionOrderStatusUpdate : Display an error

[flow10000]

Hi,

 

I'm actually working on an addon and I want to use hookActionOrderStatusUpdate.

In specific cases, I want no changes in the status and display an error in the admin product page.

 

I use that code : 

if($statusMustNotChange){
Tools::redirect($_SERVER['HTTP_REFERER']);
// How to print an error on the return page ?
}

1 - Is "Tools::redirect($_SERVER['HTTP_REFERER']);" a good way to do what I want ?

2 - How do I print an error on the return page ?

 

Thanks for help