Add showdocument hook

htdocs/core/class/html.formfile.class.php

@@ -391,6 +391,20 @@ class FormFile
 		global $langs, $conf, $user, $hookmanager;
 		global $form;
 
+		$reshook = 0;
+		if (is_object($hookmanager)){
+			$parameters = array();
++			$reshook = $hookmanager->executeHooks('showdocuments', $parameters, $object);	
+			// May report error
+			if ($reshook < 0) {
+				setEventMessages($hookmanager->error, $hookmanager->errors, 'errors');
+			} 
+		}
+		// Remode default action if $reskook > 0
+		if ($reshook > 0) {
+			return '';
+		}
+
 		if (!is_object($form)) {
 			$form = new Form($this->db);
 		}