Add BetterFlyout

StabilityMatrix.Avalonia/Controls/BetterFlyout.cs

@@ -0,0 +1,40 @@
+using System.Diagnostics.CodeAnalysis;
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Controls.Primitives;
+using Avalonia.VisualTree;
+
+namespace StabilityMatrix.Avalonia.Controls;
+
+[SuppressMessage("ReSharper", "MemberCanBePrivate.Global")]
+public class BetterFlyout : Flyout
+{
+    public static readonly StyledProperty<ScrollBarVisibility> VerticalScrollBarVisibilityProperty = AvaloniaProperty.Register<BetterFlyout, ScrollBarVisibility>(
+        "VerticalScrollBarVisibility");
+
+    public ScrollBarVisibility VerticalScrollBarVisibility
+    {
+        get => GetValue(VerticalScrollBarVisibilityProperty);
+        set => SetValue(VerticalScrollBarVisibilityProperty, value);
+    }
+
+    public static readonly StyledProperty<ScrollBarVisibility> HorizontalScrollBarVisibilityProperty = AvaloniaProperty.Register<BetterFlyout, ScrollBarVisibility>(
+        "HorizontalScrollBarVisibility");
+
+    public ScrollBarVisibility HorizontalScrollBarVisibility
+    {
+        get => GetValue(HorizontalScrollBarVisibilityProperty);
+        set => SetValue(HorizontalScrollBarVisibilityProperty, value);
+    }
+    
+    protected override void OnOpened()
+    {
+        base.OnOpened();
+        var presenter = Popup.Child;
+        if (presenter.FindDescendantOfType<ScrollViewer>() is { } scrollViewer)
+        {
+            scrollViewer.VerticalScrollBarVisibility = VerticalScrollBarVisibility;
+            scrollViewer.HorizontalScrollBarVisibility = HorizontalScrollBarVisibility;
+        }
+    }
+}