Merge pull request #3060 from AvaloniaUI/fixes/menu-initially-selected

Fix first menu item showing as selected when shown

src/Avalonia.Controls/Primitives/SelectingItemsControl.cs

@@ -1088,7 +1088,9 @@ namespace Avalonia.Controls.Primitives
                 }
                 else
                 {
-                    SelectedIndex = _updateSelectedIndex != int.MinValue ? _updateSelectedIndex : 0;
+                    SelectedIndex = _updateSelectedIndex != int.MinValue ? 
+                        _updateSelectedIndex : 
+                        AlwaysSelected ? 0 : -1;
                 }
             }
         }

tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests.cs

@@ -109,6 +109,43 @@ namespace Avalonia.Controls.UnitTests.Primitives
             Assert.True(items[1].IsSelected);
         }
 
+        [Fact]
+        public void SelectedIndex_Should_Be_Minus_1_After_Initialize()
+        {
+            var items = new[]
+            {
+                new Item(),
+                new Item(),
+            };
+
+            var target = new ListBox();
+            target.BeginInit();
+            target.Items = items;
+            target.Template = Template();
+            target.EndInit();
+
+            Assert.Equal(-1, target.SelectedIndex);
+        }
+
+        [Fact]
+        public void SelectedIndex_Should_Be_0_After_Initialize_With_AlwaysSelected()
+        {
+            var items = new[]
+            {
+                new Item(),
+                new Item(),
+            };
+
+            var target = new ListBox();
+            target.BeginInit();
+            target.SelectionMode = SelectionMode.Single | SelectionMode.AlwaysSelected;
+            target.Items = items;
+            target.Template = Template();
+            target.EndInit();
+
+            Assert.Equal(0, target.SelectedIndex);
+        }
+
         [Fact]
         public void Setting_SelectedIndex_During_Initialize_Should_Select_Item_When_AlwaysSelected_Is_Used()
         {