fix: SectionPanel resizing

GSS2.UI.Core/SectionPanel.cs

@@ -241,6 +241,40 @@ public class SectionPanel : Panel
         InvalidateArrange();
     }
 
+    protected override void OnSizeChanged(SizeChangedEventArgs e)
+    {
+        if (!_initialized ||
+            e.PreviousSize.Width == 0 ||
+            e.PreviousSize.Height == 0)
+        {
+            base.OnSizeChanged(e);
+            return;
+        }
+
+        Console.WriteLine($"{e.NewSize} {e.PreviousSize}");
+
+        foreach (var (child, i) in _childIndeces)
+        {
+            var transform = child.RenderTransform as TranslateTransform;
+            if (transform is null)
+            {
+                transform = new TranslateTransform();
+                child.RenderTransform = transform;
+            }
+            Console.WriteLine($"{i} {transform}");
+            if (child.RenderTransformOrigin != RelativePoint.TopLeft)
+                child.RenderTransformOrigin = RelativePoint.TopLeft;
+
+            _ = Orientation switch
+            {
+                Orientation.Vertical => transform.Y += transform.Y == 0 ? 0 : e.PreviousSize.Height - e.NewSize.Height,
+                Orientation.Horizontal => transform.X += transform.X == 0 ? 0 : e.PreviousSize.Width - e.NewSize.Width,
+                _ => 0
+            };
+            Console.WriteLine($"{i} {transform}");
+        }
+        base.OnSizeChanged(e);
+    }
     protected override Size MeasureOverride(Size availableSize)
     {
         foreach (var child in Children)
@@ -252,19 +286,21 @@ public class SectionPanel : Panel
         if (!_initialized)
         {
             foreach (var (i, child) in Children.Enumerate())
-            {
-                var rect = Orientation switch
-                {
-                    Orientation.Vertical => new Rect(0, i * finalSize.Height, finalSize.Width, finalSize.Height),
-                    Orientation.Horizontal => new Rect(i * finalSize.Width, 0, finalSize.Width, finalSize.Height),
-                    _ => default
-                };
                 _childIndeces.Add(child, i);
-                child.Arrange(rect);
-            }
             _initialized = true;
         }
-        else if (Children.Count() > 1)
+
+        foreach (var (child, i) in _childIndeces)
+        {
+            var rect = Orientation switch
+            {
+                Orientation.Vertical => new Rect(0, i * finalSize.Height, finalSize.Width, finalSize.Height),
+                Orientation.Horizontal => new Rect(i * finalSize.Width, 0, finalSize.Width, finalSize.Height),
+                _ => default
+            };
+            child.Arrange(rect);
+        }
+        if (Children.Count() > 1)
             Dispatcher.UIThread.Post(async () => _ = ApplyOffset(finalSize, true), DispatcherPriority.Render);
 
         return finalSize;