diff -r 8c06c8b4b79d -r 563b030f1ed1 src/pyams_form/manager.py
--- a/src/pyams_form/manager.py	Wed Jan 27 16:11:32 2021 +0100
+++ b/src/pyams_form/manager.py	Mon Feb 01 13:25:18 2021 +0100
@@ -23,10 +23,14 @@
 class DialogEditFormFormManager(ContextRequestViewAdapter):
     """Form manager base class"""
 
+    dialog_class = 'modal-large'
+
     def getFields(self):
         raise NotImplementedError
 
     def update(self):
+        form = self.view
+        form.dialog_class = self.dialog_class
         AdminDialogEditForm.update(self.view)
 
     def updateWidgets(self, prefix=None):