Use design background size for event button

Commit 9c67d86 does not account for Waifu2X, but I don't want to fix this logic.
The position of the event button in the official launcher is hardcoded with a fixed offset, so there's no need for us to scale it based on the background image size.

Author: shatyuka

CollapseLauncher/Classes/GameManagement/ImageBackground/ImageBackgroundManager.Loaders.cs

@@ -275,18 +275,11 @@ private void SpawnImageLayer(Uri? overlayFilePath,
                                   converter: StaticConverter<InverseBooleanConverter>.Shared);
 
         layerElement.ImageLoaded       += LayerElementOnLoaded;
-        layerElement.CanvasSizeChanged += LayerElementCanvasSizeChanged;
         PresenterGrid?.Children.Add(layerElement);
 
         layerElement.Tag = isVideo;
     }
 
-    private void LayerElementCanvasSizeChanged(LayeredBackgroundImage layerElement, Size size)
-    {
-        CurrentElementWidth  = size.Width;
-        CurrentElementHeight = size.Height;
-    }
-
     private void LayerElementOnLoaded(LayeredBackgroundImage layerElement)
     {
         layerElement.ImageLoaded -= LayerElementOnLoaded;
@@ -297,10 +290,6 @@ private void LayerElementOnLoaded(LayeredBackgroundImage layerElement)
         foreach (UIElement element in elementToRemove)
         {
             PresenterGrid?.Children.Remove(element);
-            if (element is LayeredBackgroundImage asLayeredImage)
-            {
-                asLayeredImage.CanvasSizeChanged -= LayerElementCanvasSizeChanged;
-            }
         }
 
         if (CurrentIsEnableBackgroundAutoPlay && WindowUtility.CurrentWindowIsVisible)

CollapseLauncher/Classes/GameManagement/ImageBackground/ImageBackgroundManager.cs

@@ -302,25 +302,9 @@ private set
         }
     }
 
-    public double CurrentElementWidth
-    {
-        get;
-        set
-        {
-            field = value;
-            OnPropertyChanged();
-        }
-    } = 2560d;
+    public double DesignWidth => 2560d;
 
-    public double CurrentElementHeight
-    {
-        get;
-        set
-        {
-            field = value;
-            OnPropertyChanged();
-        }
-    } = 1440d;
+    public double DesignHeight => 1440d;
 
     /// <summary>
     /// The collection of image context sources.<br/><br/>

CollapseLauncher/XAMLs/MainApp/Pages/HomePage.xaml

@@ -184,8 +184,8 @@
             <Grid x:Name="ImageEventImgContainerGrid"
                   DataContext="{x:Bind CurrentBackgroundManager, Mode=OneWay}"
                   Visibility="{Binding CurrentSelectedBackgroundContext.IsCustom, Mode=OneWay, Converter={StaticResource InverseBooleanVisibilityConverter}}">
-                <Grid Width="{Binding CurrentElementWidth, Mode=OneWay}"
-                      Height="{Binding CurrentElementHeight, Mode=OneWay}"
+                <Grid Width="{Binding DesignWidth, Mode=OneWay}"
+                      Height="{Binding DesignHeight, Mode=OneWay}"
                       HorizontalAlignment="Center"
                       VerticalAlignment="Center">
                     <c:NonFaultyImageEx

CollapseLauncher/XAMLs/Theme/CustomControls/LayeredBackgroundImage.Events.cs

@@ -18,7 +18,6 @@ namespace CollapseLauncher.XAMLs.Theme.CustomControls;
 public partial class LayeredBackgroundImage
 {
     public event Action<LayeredBackgroundImage>? ImageLoaded;
-    public event Action<LayeredBackgroundImage, Size>? CanvasSizeChanged;
 
     #region Fields
 
@@ -407,7 +406,6 @@ private void NotifyImageLoaded()
 
         SetValue(CanvasWidthProperty,  size.Width);
         SetValue(CanvasHeightProperty, size.Height);
-        CanvasSizeChanged?.Invoke(this, size);
     }
 
     private void NotifyVideoLoaded(MediaPlayer sender, object args)