style cloning and better docs, thanks tclerckx

Author: mdipierro

docs/chapter-07.rst

@@ -1047,8 +1047,9 @@ only for fields of type “string”. ``uploadfield``, ``authorize``, and
 -  ``authorize`` can be used to require access control on the
    corresponding field, for “upload” fields only. It will be discussed
    more in detail in the context of Authentication and Authorization.
--  ``widget`` do not use DAL widgets with py4web, it has has its own
-   (see :ref:`Widgets` later).
+-  ``widget`` Do NOT use the widget parameter in py4web for a Field definition.
+   (This was a feature of web2py and is not to be used in py4web)
+   See :ref:`Widgets` later.
 -  ``represent`` can be None or can point to a function that takes a
    field value and returns an alternate representation for the field
    value.

docs/chapter-12.rst

@@ -100,8 +100,8 @@ Where:
 -  ``readonly``: set to True to make a readonly form
 -  ``deletable``: set to False to disallow deletion of record
 -  ``formstyle``: a function that renders the form using helpers.
-    Can be FormStyleDefault (default), FormStyleBulma,
-    FormStyleBootstrap4, or FormStyleBootstrap5
+    Can be ``FormStyleDefault`` (default), ``FormStyleBulma``,
+    ``FormStyleBootstrap4``, or ``FormStyleBootstrap5``.
 -  ``dbio``: set to False to prevent any DB writes
 -  ``keep_values``: if set to true, it remembers the values of the previously submitted form
 -  ``form_name``: the optional name of this form
@@ -111,6 +111,13 @@ Where:
 -  ``lifespan``: lifespan of CSRF token in seconds, to limit form validity
 -  ``signing_info``: information that should not change between when the CSRF token is signed and verified
 
+``FormStyleDefault`` is an object that is used by default for every form
+and it is defined in ``py4web.utils.form.FormStyleDefault``.
+You should never change it but you can make a copy and pass it as ``formstyle``.
+
+You can change the style of a field named, for example, ``color``
+by changing the attribute ``color`` of the FormStyle.
+
 
 A minimal form example without a database
 -----------------------------------------
@@ -352,8 +359,8 @@ Using widgets in forms is quite easy, and they'll let you have more control on i
 Custom widgets
 ~~~~~~~~~~~~~~
 
-You can also customize the widgets properties by subclassing the FormStyleDefault class. Let's have a quick look,
-improving again our Superhero example:
+You can also customize the widgets properties by cloning an modifying and existing style.
+Let's have a quick look, improving again our Superhero example:
 
 .. code:: python
 
@@ -383,7 +390,7 @@ improving again our Superhero example:
     @action("create_form", method=["GET", "POST"])
     @action.uses("form_custom_widgets.html", db)
     def create_form():
-        MyStyle = FormStyleDefault
+        MyStyle = FormStyleDefault.clone()
         MyStyle.classes = FormStyleDefault.classes
         MyStyle.widgets['name']=MyCustomWidget()
         MyStyle.widgets['color']=RadioWidget()

py4web/utils/form.py

@@ -280,6 +280,9 @@ def __init__(self):
         self.class_inner_exceptions = copy.copy(self._class_inner_exceptions)
         self.widgets = copy.copy(self._widgets)
 
+    def clone(self):
+        return copy.deepcopy(self)
+
     def __call__(
         self,
         table,