In order to include the right file and display an error page if an error occurs, I have the following code (very simplified) :
$page = 'examplePage.php';
$page404 = '404.php';
if (file_exists($page))
{
    require($page);
}
else if (file_exists($page404))
{
    require($page404);
}
else
{
    // Tell the browser to display his default page
}
?>
To summarize :
- If I have the file, I include it. 
- If I don't have the file, i include the error file. 
- What if the error file does not exist too ? 
I would like it to be rendered as the default error page of the browser.
I already achieved this with Internet Explorer by sending an empty content with the HTTP error. The problem is that the other browsers don't act the same, they all display a blank page.
Is there any way to tell browsers to display their own error page ? (not only 404, but all errors : 304, 500 etc)
Thank you.
Edit : I forgot to tell you that I have the complete control on the headers I send and on the content sent in response.
Edit 2 : here is some code
// possible paths to retrieve the file
$possiblePaths = array(
    $urlPath,
    D_ROOT.$urlPath,
    D_PAGES.$urlPath.'.php',
    D_PAGES.$urlPath.'/index.php',
    $urlPath.'.php'
);
foreach ($possiblePaths as $possiblePath)
    if (file_exists($possiblePath) && !is_dir($possiblePath))
    {
        if (!is_readable($possiblePath))
        {
            Response::setCode(403); // calls the header(403)
            self::$filePath = self::getErrorPage(403);
        }
        else
            self::$filePath = $possiblePath;
        break;
    }
if (self::$filePath === null) // no file found => 404
{
    Response::setCode(404); // call the header(404)
    self::$filePath = self::getErrorPage(404); 
}
public static function _getErrorPage($code)
{
    if (is_readable(D_ERRORS.$code.'.php')) // D_ERRORS is the error directory, it contains files like 404.php, 403.php etc
        return D_ERRORS.$code.'.php';
    else
    {
        /*-------------------------------------------------*/
        /* Here i go if the error file is not found either */
        /*-------------------------------------------------*/
        if ($code >= 400)
            Response::$dieResponse = true; // removes all output, only leaves the http header
        return null;
    }
}
?>
And here is when I print the content :
    <?php
    if (self::$dieResponse)
    {
        self::$headers = array(); // no more headers
        self::$content = ''; // no more response
    }
    http_response_code(self::$code); // HTTP code
    foreach (self::$headers as $key => $value)
        header($key.': '.implode(';', $value)); // sends all headers
    echo self::$content;
    ?>
Edit : here are some screenshots to explain what I want.
This is what i've got in IE :

This is exactly what i want.
Now, in all the other browsers, I've got a blank page. I don't want a blank page.
I want, for example, Chrome to display this :

 
     
     
     
     
    