DateTimePicker has incorrect AccessKey and KeyboardShortcut accessibi…

…lity properties when Text contains '&' character (#9414)

* fix DateTimePicker has incorrect AccessKey and KeyboardShortcut accessibility properties when Text contains '&' character #9281

* add comment, remove redundant code

* fix wrong case - Win32

src/System.Windows.Forms/src/System/Windows/Forms/DateTimePicker.DateTimePickerAccessibleObject.cs

@@ -32,18 +32,8 @@ public override string? KeyboardShortcut
                     }
                 }
 
-                string? baseShortcut = base.KeyboardShortcut;
-
-                if (baseShortcut is null || baseShortcut.Length == 0)
-                {
-                    char ownerTextMnemonic = WindowsFormsUtils.GetMnemonic(this.GetOwnerText(), convertToUpperCase: false);
-                    if (ownerTextMnemonic != '\0')
-                    {
-                        return $"Alt+{ownerTextMnemonic}";
-                    }
-                }
-
-                return baseShortcut;
+                // Win32 DTP does not interpret ampersand in its Text as an escape character for a mnemonic.
+                return null;
             }
         }
 

src/System.Windows.Forms/tests/UnitTests/System/Windows/Forms/DateTimePicker.DateTimePickerAccessibleObjectTests.cs

@@ -342,4 +342,35 @@ public void DateTimePickerAccessibleObject_DoDefaultAction_IfHandleIsCreated_Ret
         Assert.Equal((UiaCore.ExpandCollapseState)expected, accessibleObject.ExpandCollapseState);
         Assert.True(dateTimePicker.IsHandleCreated);
     }
+
+    // Unit Test for https://github.com/dotnet/winforms/issues/9281.
+    [WinFormsFact]
+    public void DateTimePickerAccessibleObject_KeyboardShortcut_ReturnsExpected()
+    {
+        using Form form = new Form();
+        using DateTimePicker dateTimePicker1 = new();
+        using Label label1 = new ();
+        using DateTimePicker dateTimePicker2 = new();
+
+        dateTimePicker1.CustomFormat = "'Date&Time' hh:mm dd/MM";
+        dateTimePicker1.Format = DateTimePickerFormat.Custom;
+        dateTimePicker1.TabIndex = 0;
+
+        label1.Text = "&Date";
+        label1.TabIndex = 1;
+
+        dateTimePicker2.TabIndex = 2;
+
+        form.Controls.Add(dateTimePicker2);
+        form.Controls.Add(label1);
+        form.Controls.Add(dateTimePicker1);
+
+        string keyboardShortcut = dateTimePicker1.AccessibilityObject.KeyboardShortcut;
+
+        Assert.Null(keyboardShortcut);
+
+        keyboardShortcut = dateTimePicker2.AccessibilityObject.KeyboardShortcut;
+
+        Assert.Equal("Alt+d", keyboardShortcut);
+    }
 }