OWWidget: Deprecate buttons_area_orientation

Author: ales-erjavec

Orange/widgets/widget.py

@@ -4,6 +4,7 @@
 import sys
 import os
 import types
+import warnings
 
 from AnyQt.QtWidgets import (
     QWidget, QDialog, QVBoxLayout, QSizePolicy, QApplication, QStyle,
@@ -66,6 +67,14 @@ def __new__(mcs, name, bases, kwargs):
         return cls
 
 
+class _NoValue:
+    """No value (not set) marker."""
+    def __repr__(self):
+        return "<No Value>"
+
+_NoValue = _NoValue()
+
+
 class OWWidget(QDialog, OWComponent, Report, ProgressBarMixin,
                WidgetMessagesMixin, WidgetSignalsMixin,
                metaclass=WidgetMetaClass):
@@ -115,10 +124,15 @@ class OWWidget(QDialog, OWComponent, Report, ProgressBarMixin,
     want_main_area = True
     #: Should the widget construct a `controlArea`.
     want_control_area = True
+
     #: Orientation of the buttonsArea box; valid only if
     #: `want_control_area` is `True`. Possible values are Qt.Horizontal,
     #: Qt.Vertical and None for no buttons area
-    buttons_area_orientation = Qt.Horizontal
+    #:
+    #: .. deprecated:: 3.5.0
+    #:    `buttonsArea` is deprecate and (by default) unused.
+    buttons_area_orientation = _NoValue
+
     #: Specify whether the default message bar widget should be created
     #: and placed into the default layout. If False then clients are
     #: responsible for displaying messages within the widget in an
@@ -281,6 +295,13 @@ def _insert_splitter(self):
     def _insert_control_area(self):
         self.left_side = gui.vBox(self.splitter, spacing=0)
         self.splitter.setSizes([1])  # Smallest size allowed by policy
+        if self.buttons_area_orientation is not _NoValue:
+            warnings.warn(
+                "`buttons_area_orientation` (and consequently `buttonArea`) "
+                "is deprecated and will be removed in the future",
+                category=DeprecationWarning,
+            )
+
         if self.buttons_area_orientation is not None:
             self.controlArea = gui.vBox(self.left_side, addSpace=0)
             self._insert_buttons_area()
@@ -295,9 +316,13 @@ def _insert_control_area(self):
         self.controlArea.layout().setContentsMargins(m, m, m, m)
 
     def _insert_buttons_area(self):
+        if self.buttons_area_orientation is _NoValue:
+            orientation = Qt.Horizontal
+        else:
+            orientation = self.buttons_area_orientation
         self.buttonsArea = gui.widgetBox(
             self.left_side, addSpace=0, spacing=9,
-            orientation=self.buttons_area_orientation)
+            orientation=orientation)
 
     def _insert_main_area(self):
         self.mainArea = gui.vBox(