Fix XamlRoot being set incorrectly in Popup Handler (#2476)

* Fix XamlRoot being set incorrectly in Popup Handler when using modal navigation in Windows

* Updated `PopupSizeConstants` to not make sample app popup size too large when testing Mulitple popups page

Author: ne0rrmatrix

samples/CommunityToolkit.Maui.Sample/Models/PopupSize.cs

@@ -6,8 +6,8 @@ public PopupSizeConstants(IDeviceDisplay deviceDisplay)
 	{
 		Tiny = new(100, 100);
 		Small = new(300, 300);
-		Medium = new(0.7 * (deviceDisplay.MainDisplayInfo.Width / deviceDisplay.MainDisplayInfo.Density), 0.6 * (deviceDisplay.MainDisplayInfo.Height / deviceDisplay.MainDisplayInfo.Density));
-		Large = new(0.9 * (deviceDisplay.MainDisplayInfo.Width / deviceDisplay.MainDisplayInfo.Density), 0.8 * (deviceDisplay.MainDisplayInfo.Height / deviceDisplay.MainDisplayInfo.Density));
+		Medium = new(0.4 * (deviceDisplay.MainDisplayInfo.Width / deviceDisplay.MainDisplayInfo.Density), 0.6 * (deviceDisplay.MainDisplayInfo.Height / deviceDisplay.MainDisplayInfo.Density));
+		Large = new(0.5 * (deviceDisplay.MainDisplayInfo.Width / deviceDisplay.MainDisplayInfo.Density), 0.8 * (deviceDisplay.MainDisplayInfo.Height / deviceDisplay.MainDisplayInfo.Density));
 	}
 
 	// examples for fixed sizes

src/CommunityToolkit.Maui.Core/Handlers/Popup/PopUpHandler.windows.cs

@@ -41,9 +41,8 @@ public static void MapOnOpened(PopupHandler handler, IPopup view, object? result
 		ArgumentNullException.ThrowIfNull(handler.MauiContext);
 
 		var parent = view.Parent.ToPlatform(handler.MauiContext);
-
 		parent.IsHitTestVisible = false;
-		handler.PlatformView.XamlRoot = parent.XamlRoot;
+		handler.PlatformView.XamlRoot = view.GetWindow().Content?.Handler?.MauiContext?.GetPlatformWindow().Content.XamlRoot ?? throw new InvalidOperationException("Window Content cannot be null");
 		handler.PlatformView.IsHitTestVisible = true;
 		handler.PlatformView.IsOpen = true;