Add DeprecationWarning to the deprecated methods

most IDE's will recognize it and annotate during new code usage
call with "warnings as errors" mode will help to refactor other users

urwid/display_common.py

@@ -23,6 +23,7 @@
 
 import os
 import sys
+import warnings
 
 try:
     import termios
@@ -869,10 +870,13 @@ def run_wrapper(self, fn, *args, **kwargs):
 
         Deprecated in favor of calling `start` as a context manager.
         """
+        warnings.warn(
+            "run_wrapper is deprecated in favor of calling `start` as a context manager.",
+            DeprecationWarning,
+        )
         with self.start(*args, **kwargs):
             return fn()
 
-
     def register_palette(self, palette):
         """Register a set of palette entries.
 

urwid/signals.py

@@ -23,6 +23,7 @@
 from __future__ import annotations
 
 import itertools
+import warnings
 import weakref
 
 
@@ -149,6 +150,11 @@ def connect(self, obj, name, callback, user_arg=None, weak_args=None, user_args=
         handler can also be disconnected by calling
         urwid.disconnect_signal, which doesn't need this key.
         """
+        if user_arg is not None:
+            warnings.warn(
+                "Don't use user_arg argument, use user_args instead.",
+                DeprecationWarning,
+            )
 
         sig_cls = obj.__class__
         if not name in self._supported.get(sig_cls, []):

urwid/widget.py

@@ -22,6 +22,7 @@
 
 from __future__ import annotations
 
+import warnings
 from operator import attrgetter
 
 from urwid import signals, text_layout
@@ -623,6 +624,17 @@ class FlowWidget(Widget):
     """
     _sizing = frozenset([FLOW])
 
+    def __init__(self, *args, **kwargs):
+        warnings.warn(
+            """
+            FlowWidget is deprecated. Inherit from Widget and add:
+
+                _sizing = frozenset(['flow'])
+
+            at the top of your class definition instead.""",
+            DeprecationWarning,
+        )
+
     def rows(self, size, focus=False):
         """
         All flow widgets must implement this function.
@@ -651,6 +663,18 @@ class BoxWidget(Widget):
     _selectable = True
     _sizing = frozenset([BOX])
 
+    def __init__(self, *args, **kwargs):
+        warnings.warn(
+            """
+            BoxWidget is deprecated. Inherit from Widget and add:
+
+                _sizing = frozenset(['box'])
+                _selectable = True
+
+            at the top of your class definition instead.""",
+            DeprecationWarning,
+        )
+
     def render(self, size, focus=False):
         """
         All widgets must implement this function.
@@ -680,6 +704,17 @@ class FixedWidget(Widget):
     """
     _sizing = frozenset([FIXED])
 
+    def __init__(self, *args, **kwargs):
+        warnings.warn(
+            """
+            FixedWidget is deprecated. Inherit from Widget and add:
+
+                _sizing = frozenset(['fixed'])
+
+            at the top of your class definition instead.""",
+            DeprecationWarning,
+        )
+
     def render(self, size, focus=False):
         """
         All widgets must implement this function.