fix Automation.HelpText on windows (#17030)

* fix Automation.HelpText on windows

* change breaking abstract to virtual

* only fall back to tooltip if string

* remove duplicate override

---------

Co-authored-by: Benedikt Stebner <Gillibald@users.noreply.github.com>

src/Avalonia.Controls/Automation/AutomationElementIdentifiers.cs

@@ -24,5 +24,11 @@ namespace Avalonia.Automation
         /// by the <see cref="AutomationPeer.GetName"/> method.
         /// </summary>
         public static AutomationProperty NameProperty { get; } = new AutomationProperty();
+
+        /// <summary>
+        /// Identifies the helpText automation property. The class name property value is returned
+        /// by the <see cref="AutomationPeer.GetHelpText"/> method.
+        /// </summary>
+        public static AutomationProperty HelpTextProperty { get; } = new AutomationProperty();
     }
 }

src/Avalonia.Controls/Automation/Peers/AutomationPeer.cs

@@ -112,6 +112,11 @@ namespace Avalonia.Automation.Peers
         /// Gets text that describes the element that is associated with this automation peer.
         /// </summary>
         public string GetName() => GetNameCore() ?? string.Empty;
+        
+        /// <summary>
+        /// Gets text that provides help for the element that is associated with this automation peer.
+        /// </summary>
+        public string GetHelpText() => GetHelpTextCore() ?? string.Empty;
 
         /// <summary>
         /// Gets the <see cref="AutomationPeer"/> that is the parent of this <see cref="AutomationPeer"/>.
@@ -250,6 +255,7 @@ namespace Avalonia.Automation.Peers
         protected abstract string GetClassNameCore();
         protected abstract AutomationPeer? GetLabeledByCore();
         protected abstract string? GetNameCore();
+        protected virtual string? GetHelpTextCore() => null;
         protected abstract AutomationPeer? GetParentCore();
         protected abstract bool HasKeyboardFocusCore();
         protected abstract bool IsContentElementCore();

src/Avalonia.Controls/Automation/Peers/ControlAutomationPeer.cs

@@ -116,7 +116,17 @@ namespace Avalonia.Automation.Peers
 
             return result;
         }
+        protected override string? GetHelpTextCore()
+        {          
+            var result = AutomationProperties.GetHelpText(Owner);
 
+            if (string.IsNullOrWhiteSpace(result))
+            {
+                result = ToolTip.GetTip(Owner) as string;
+            }
+
+            return result;          
+        }
         protected override AutomationPeer? GetParentCore()
         {
             EnsureConnected();

src/Avalonia.Controls/Automation/Peers/InteropAutomationPeer.cs

@@ -28,6 +28,7 @@ internal class InteropAutomationPeer : AutomationPeer
     protected override string GetClassNameCore() => throw new NotImplementedException();
     protected override AutomationPeer? GetLabeledByCore() => throw new NotImplementedException();
     protected override string? GetNameCore() => throw new NotImplementedException();
+    protected override string? GetHelpTextCore() => throw new NotImplementedException();
     protected override IReadOnlyList<AutomationPeer> GetOrCreateChildrenCore() => throw new NotImplementedException();
     protected override AutomationPeer? GetParentCore() => _parent;
     protected override bool HasKeyboardFocusCore() => throw new NotImplementedException();

src/Avalonia.Controls/Automation/Peers/UnrealizedElementAutomationPeer.cs

@@ -20,5 +20,6 @@ namespace Avalonia.Automation.Peers
         protected override void SetFocusCore() { }
         protected override bool ShowContextMenuCore() => false;
         protected internal override bool TrySetParent(AutomationPeer? parent) => false;
+                
     }
 }

src/Windows/Avalonia.Win32/Automation/AutomationNode.cs

@@ -28,6 +28,7 @@ namespace Avalonia.Win32.Automation
             { AutomationElementIdentifiers.BoundingRectangleProperty, UiaPropertyId.BoundingRectangle },
             { AutomationElementIdentifiers.ClassNameProperty, UiaPropertyId.ClassName },
             { AutomationElementIdentifiers.NameProperty, UiaPropertyId.Name },
+            { AutomationElementIdentifiers.HelpTextProperty, UiaPropertyId.HelpText },
             { ExpandCollapsePatternIdentifiers.ExpandCollapseStateProperty, UiaPropertyId.ExpandCollapseExpandCollapseState },
             { RangeValuePatternIdentifiers.IsReadOnlyProperty, UiaPropertyId.RangeValueIsReadOnly},
             { RangeValuePatternIdentifiers.MaximumProperty, UiaPropertyId.RangeValueMaximum },
@@ -122,6 +123,7 @@ namespace Avalonia.Win32.Automation
                 UiaPropertyId.IsOffscreen => InvokeSync(() => Peer.IsOffscreen()),
                 UiaPropertyId.LocalizedControlType => InvokeSync(() => Peer.GetLocalizedControlType()),
                 UiaPropertyId.Name => InvokeSync(() => Peer.GetName()),
+                UiaPropertyId.HelpText => InvokeSync(() => Peer.GetHelpText()),
                 UiaPropertyId.ProcessId => Process.GetCurrentProcess().Id,
                 UiaPropertyId.RuntimeId => _runtimeId,
                 _ => null,