add:PPT时间胶囊（没做完不好看）

Ink Canvas/Helpers/Converters.cs

@@ -135,4 +135,21 @@ namespace Ink_Canvas.Converter
             return Visibility.Visible;
         }
     }
+
+    public class RippleEffectTranslationConverter : IValueConverter
+    {
+        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (value is double d)
+            {
+                return -d / 2;
+            }
+            return 0.0;
+        }
+
+        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            return null;
+        }
+    }
 }

Ink Canvas/Helpers/PPTUIManager.cs

@@ -101,6 +101,7 @@ namespace Ink_Canvas.Helpers
 
                         UpdateNavigationPanelsVisibility();
                         UpdateNavigationButtonStyles();
+                        _mainWindow.UpdatePPTTimeCapsuleVisibility();
                         if (MainWindow.Settings.Advanced.IsEnableAvoidFullScreenHelper)
                         {
                             // 设置为画板模式，允许全屏操作
@@ -120,6 +121,7 @@ namespace Ink_Canvas.Helpers
                         _mainWindow.BtnPPTSlideShow.Visibility = Visibility.Visible;
                         _mainWindow.BtnPPTSlideShowEnd.Visibility = Visibility.Collapsed;
                         HideAllNavigationPanels();
+                        _mainWindow.UpdatePPTTimeCapsuleVisibility();
                         if (MainWindow.Settings.Advanced.IsEnableAvoidFullScreenHelper)
                         {
                             // 恢复为非画板模式，重新启用全屏限制