Refactor InitProgressbarAnimation & avoid style cast issue

Flow.Launcher/MainWindow.xaml

@@ -337,6 +337,7 @@
                 </Border>
                 <Line
                     x:Name="ProgressBar"
+                    Style="{DynamicResource PendingLineStyle}"
                     Width="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Grid}}, Path=ActualWidth}"
                     Height="2"
                     Margin="12 0 12 0"

Flow.Launcher/MainWindow.xaml.cs

@@ -75,6 +75,7 @@ public partial class MainWindow : IDisposable
         // Window Animation
         private const double DefaultRightMargin = 66; //* this value from base.xaml
         private bool _isClockPanelAnimating = false;
+        private Storyboard _progressBarStoryboard;
 
         // IDisposable
         private bool _disposed = false;
@@ -1120,49 +1121,58 @@ private double VerticalTop(MonitorInfo screen)
 
         private void InitProgressbarAnimation()
         {
-            var progressBarStoryBoard = new Storyboard();
+            _progressBarStoryboard = new Storyboard();
 
-            var da = new DoubleAnimation(ProgressBar.X2, ActualWidth + 100,
-                new Duration(new TimeSpan(0, 0, 0, 0, 1600)));
-            var da1 = new DoubleAnimation(ProgressBar.X1, ActualWidth + 0,
-                new Duration(new TimeSpan(0, 0, 0, 0, 1600)));
-            Storyboard.SetTargetProperty(da, new PropertyPath("(Line.X2)"));
-            Storyboard.SetTargetProperty(da1, new PropertyPath("(Line.X1)"));
-            progressBarStoryBoard.Children.Add(da);
-            progressBarStoryBoard.Children.Add(da1);
-            progressBarStoryBoard.RepeatBehavior = RepeatBehavior.Forever;
+            var animationDuration = new Duration(TimeSpan.FromMilliseconds(1600));
+            var progressBarLength = ProgressBar.X2 - ProgressBar.X1;
 
-            da.Freeze();
-            da1.Freeze();
-
-            const string progressBarAnimationName = "ProgressBarAnimation";
-            var beginStoryboard = new BeginStoryboard
+            var lineEndAnimation = new DoubleAnimation
             {
-                Name = progressBarAnimationName, Storyboard = progressBarStoryBoard
+                From = ProgressBar.X2,
+                To = ProgressBar.ActualWidth + progressBarLength,
+                Duration = animationDuration
             };
-
-            var stopStoryboard = new StopStoryboard()
+            var lineStartAnimation = new DoubleAnimation
             {
-                BeginStoryboardName = progressBarAnimationName
+                From = ProgressBar.X1,
+                To = ProgressBar.ActualWidth,
+                Duration = animationDuration
             };
+
+            Storyboard.SetTarget(lineEndAnimation, ProgressBar);
+            Storyboard.SetTargetProperty(lineEndAnimation, new PropertyPath("(Line.X2)"));
+
+            Storyboard.SetTarget(lineStartAnimation, ProgressBar);
+            Storyboard.SetTargetProperty(lineStartAnimation, new PropertyPath("(Line.X1)"));
+
+            _progressBarStoryboard.Children.Add(lineEndAnimation);
+            _progressBarStoryboard.Children.Add(lineStartAnimation);
+            _progressBarStoryboard.RepeatBehavior = RepeatBehavior.Forever;
+
+            lineEndAnimation.Freeze();
+            lineStartAnimation.Freeze();
+
+            ProgressBar.IsVisibleChanged -= ProgressBar_IsVisibleChanged;
+            ProgressBar.IsVisibleChanged += ProgressBar_IsVisibleChanged;
 
-            var trigger = new Trigger
-            {
-                Property = VisibilityProperty, Value = Visibility.Visible
-            };
-            trigger.EnterActions.Add(beginStoryboard);
-            trigger.ExitActions.Add(stopStoryboard);
+            _viewModel.ProgressBarVisibility = Visibility.Hidden;
+        }
 
-            var progressStyle = new Style(typeof(Line))
+        private void ProgressBar_IsVisibleChanged(object sender, DependencyPropertyChangedEventArgs e)
+        {
+            if (_progressBarStoryboard == null)
             {
-                BasedOn = FindResource("PendingLineStyle") as Style
-            };
-            progressStyle.RegisterName(progressBarAnimationName, beginStoryboard);
-            progressStyle.Triggers.Add(trigger);
-
-            ProgressBar.Style = progressStyle;
+                return;
+            }
 
-            _viewModel.ProgressBarVisibility = Visibility.Hidden;
+            if (ProgressBar.IsVisible)
+            {
+                _progressBarStoryboard.Begin(ProgressBar, true);
+            }
+            else
+            {
+                _progressBarStoryboard.Stop(ProgressBar);
+            }
         }
 
         private void WindowAnimation()