diff --git a/src/AppCommon/FileTime.App.Core.Abstraction/ViewModels/Timeline/ICommandTimeStateViewModel.cs b/src/AppCommon/FileTime.App.Core.Abstraction/ViewModels/Timeline/ICommandTimeStateViewModel.cs
index 59d12c3..700c12f 100644
--- a/src/AppCommon/FileTime.App.Core.Abstraction/ViewModels/Timeline/ICommandTimeStateViewModel.cs
+++ b/src/AppCommon/FileTime.App.Core.Abstraction/ViewModels/Timeline/ICommandTimeStateViewModel.cs
@@ -1,11 +1,13 @@
+using DeclarativeProperty;
+
 namespace FileTime.App.Core.ViewModels.Timeline;
 
 public interface ICommandTimeStateViewModel
 {
-    IObservable<int> TotalProgress { get; }
-    IObservable<int> CurrentProgress { get; }
-    IObservable<string> DisplayLabel { get; }
-    IObservable<string> DisplayDetailLabel { get; }
-    IObservable<bool> IsSelected { get; }
+    IDeclarativeProperty<int> TotalProgress { get; }
+    IDeclarativeProperty<int> CurrentProgress { get; }
+    IDeclarativeProperty<string> DisplayLabel { get; }
+    IDeclarativeProperty<string> DisplayDetailLabel { get; }
+    IDeclarativeProperty<bool> IsSelected { get; }
     void Cancel();
 }
\ No newline at end of file
diff --git a/src/AppCommon/FileTime.App.Core/ViewModels/Timeline/CommandTimeStateViewModel.cs b/src/AppCommon/FileTime.App.Core/ViewModels/Timeline/CommandTimeStateViewModel.cs
index f6765c4..6ca2c5e 100644
--- a/src/AppCommon/FileTime.App.Core/ViewModels/Timeline/CommandTimeStateViewModel.cs
+++ b/src/AppCommon/FileTime.App.Core/ViewModels/Timeline/CommandTimeStateViewModel.cs
@@ -1,4 +1,5 @@
 using System.Reactive.Subjects;
+using DeclarativeProperty;
 using FileTime.Core.Timeline;
 
 namespace FileTime.App.Core.ViewModels.Timeline;
@@ -6,13 +7,13 @@ namespace FileTime.App.Core.ViewModels.Timeline;
 public class CommandTimeStateViewModel : ICommandTimeStateViewModel
 {
     private readonly CommandTimeState _commandTimeState;
-    public IObservable<int> TotalProgress { get; }
-    public IObservable<int> CurrentProgress { get; }
+    public IDeclarativeProperty<int> TotalProgress { get; }
+    public IDeclarativeProperty<int> CurrentProgress { get; }
 
-    public IObservable<string> DisplayLabel { get; }
-    public IObservable<string> DisplayDetailLabel { get; }
+    public IDeclarativeProperty<string> DisplayLabel { get; }
+    public IDeclarativeProperty<string> DisplayDetailLabel { get; }
 
-    public IObservable<bool> IsSelected { get; }
+    public IDeclarativeProperty<bool> IsSelected { get; }
 
     public CommandTimeStateViewModel(CommandTimeState commandTimeState)
     {
@@ -22,7 +23,7 @@ public class CommandTimeStateViewModel : ICommandTimeStateViewModel
         TotalProgress = commandTimeState.Command.TotalProgress;
         CurrentProgress = commandTimeState.Command.CurrentProgress;
         //TODO
-        IsSelected = new BehaviorSubject<bool>(false);
+        IsSelected = new DeclarativeProperty<bool>(false);
     }
 
     public void Cancel()
diff --git a/src/Core/FileTime.Core.Abstraction/Command/ICommand.cs b/src/Core/FileTime.Core.Abstraction/Command/ICommand.cs
index 2fcde92..64b9a09 100644
--- a/src/Core/FileTime.Core.Abstraction/Command/ICommand.cs
+++ b/src/Core/FileTime.Core.Abstraction/Command/ICommand.cs
@@ -1,13 +1,14 @@
+using DeclarativeProperty;
 using FileTime.Core.Timeline;
 
 namespace FileTime.Core.Command;
 
 public interface ICommand
 {
-    IObservable<string> DisplayLabel { get; }
-    IObservable<string> DisplayDetailLabel { get; }
-    IObservable<int> TotalProgress { get; }
-    IObservable<int> CurrentProgress { get; }
+    IDeclarativeProperty<string> DisplayLabel { get; }
+    IDeclarativeProperty<string> DisplayDetailLabel { get; }
+    IDeclarativeProperty<int> TotalProgress { get; }
+    IDeclarativeProperty<int> CurrentProgress { get; }
 
     Task<CanCommandRun> CanRun(PointInTime currentTime);
     Task<PointInTime> SimulateCommand(PointInTime currentTime);
diff --git a/src/Core/FileTime.Core.Command/CommandBase.cs b/src/Core/FileTime.Core.Command/CommandBase.cs
index dafab62..89fbe79 100644
--- a/src/Core/FileTime.Core.Command/CommandBase.cs
+++ b/src/Core/FileTime.Core.Command/CommandBase.cs
@@ -1,20 +1,21 @@
 using System.Reactive.Linq;
 using System.Reactive.Subjects;
+using DeclarativeProperty;
 using FileTime.Core.Timeline;
 
 namespace FileTime.Core.Command;
 
 public abstract class CommandBase : ICommand
 {
-    private readonly BehaviorSubject<string> _displayLabel;
-    private readonly BehaviorSubject<string> _displayDetailLabel;
-    private readonly BehaviorSubject<int> _totalProgress;
-    private readonly BehaviorSubject<int> _currentProgress;
+    private readonly DeclarativeProperty<string> _displayLabel;
+    private readonly DeclarativeProperty<string> _displayDetailLabel;
+    private readonly DeclarativeProperty<int> _totalProgress;
+    private readonly DeclarativeProperty<int> _currentProgress;
 
-    public IObservable<string> DisplayLabel { get; }
-    public IObservable<string> DisplayDetailLabel { get; }
-    public IObservable<int> TotalProgress { get; }
-    public IObservable<int> CurrentProgress { get; }
+    public IDeclarativeProperty<string> DisplayLabel { get; }
+    public IDeclarativeProperty<string> DisplayDetailLabel { get; }
+    public IDeclarativeProperty<int> TotalProgress { get; }
+    public IDeclarativeProperty<int> CurrentProgress { get; }
 
     protected CommandBase(string displayLabel = "", string displayDetailLabel = "", int totalProgress = 0, int currentProgress = 0)
     {
@@ -23,32 +24,32 @@ public abstract class CommandBase : ICommand
         _totalProgress = new(totalProgress);
         _currentProgress = new(currentProgress);
 
-        DisplayLabel = _displayLabel.AsObservable();
-        DisplayDetailLabel = _displayDetailLabel.AsObservable();
-        TotalProgress = _totalProgress.AsObservable();
-        CurrentProgress = _currentProgress.AsObservable();
+        DisplayLabel = _displayLabel;
+        DisplayDetailLabel = _displayDetailLabel;
+        TotalProgress = _totalProgress;
+        CurrentProgress = _currentProgress;
     }
 
     public abstract Task<CanCommandRun> CanRun(PointInTime currentTime);
     public abstract Task<PointInTime> SimulateCommand(PointInTime currentTime);
     public abstract void Cancel();
 
-    protected void SetDisplayLabel(string? displayLabel) => _displayLabel.OnNext(displayLabel ?? string.Empty);
-    protected void SetDisplayDetailLabel(string? displayLabel) => _displayDetailLabel.OnNext(displayLabel ?? string.Empty);
+    protected async Task SetDisplayLabelAsync(string? displayLabel) => await _displayLabel.SetValue(displayLabel ?? string.Empty);
+    protected async Task SetDisplayDetailLabel(string? displayLabel) => await _displayDetailLabel.SetValue(displayLabel ?? string.Empty);
 
-    protected void SetTotalProgress(int totalProgress) => _totalProgress.OnNext(totalProgress);
+    protected async Task SetTotalProgress(int totalProgress) => await _totalProgress.SetValue(totalProgress);
 
-    protected void SetCurrentProgress(int currentProgress) => _currentProgress.OnNext(currentProgress);
+    protected async Task SetCurrentProgress(int currentProgress) => await _currentProgress.SetValue(currentProgress);
 
     protected IDisposable TrackProgress(IEnumerable<OperationProgress> operationProgresses) =>
         operationProgresses
-            .Select(op => op.Progress.Select(p => (Progress: p, TotalProgress: op.TotalCount)))
-            .CombineLatest()
-            .Select(data =>
+            .Select(op => op.Progress.Map(p => (Progress: p, TotalProgress: op.TotalCount)))
+            .CombineAll(data =>
             {
-                var total = data.Sum(d => d.TotalProgress);
-                if (total == 0) return 0;
-                return (int) (data.Sum(d => d.Progress) * 100 / total);
+                var dataList = data.ToList();
+                var total = dataList.Sum(d => d.TotalProgress);
+                if (total == 0) return Task.FromResult(0);
+                return Task.FromResult((int)(dataList.Sum(d => d.Progress) * 100 / total));
             })
-            .Subscribe(SetTotalProgress);
+            .Subscribe(async (p, _) => await SetTotalProgress(p));
 }
\ No newline at end of file
diff --git a/src/Core/FileTime.Core.Command/Copy/CopyCommand.cs b/src/Core/FileTime.Core.Command/Copy/CopyCommand.cs
index 13ee8d6..2498c12 100644
--- a/src/Core/FileTime.Core.Command/Copy/CopyCommand.cs
+++ b/src/Core/FileTime.Core.Command/Copy/CopyCommand.cs
@@ -17,7 +17,7 @@ public class CopyCommand : CommandBase, ITransportationCommand
     private readonly CancellationTokenSource _cancellationTokenSource = new();
 
     private readonly List<OperationProgress> _operationProgresses = new();
-    private readonly BehaviorSubject<OperationProgress?> _currentOperationProgress = new(null);
+    private readonly DeclarativeProperty<OperationProgress?> _currentOperationProgress = new();
 
     private long _recentTotalSum;
     private readonly DeclarativeProperty<long> _recentTotalProcessed = new();
@@ -41,22 +41,21 @@ public class CopyCommand : CommandBase, ITransportationCommand
         ArgumentNullException.ThrowIfNull(sources);
         ArgumentNullException.ThrowIfNull(mode);
         ArgumentNullException.ThrowIfNull(targetFullName);
-        
+
         _timelessContentProvider = timelessContentProvider;
         _commandSchedulerNotifier = commandSchedulerNotifier;
         _logger = logger;
         _currentOperationProgress
-            .Select(p =>
+            .Map(p =>
             {
-                if (p is null) return Observable.Never<int>();
-                return p.Progress.Select(currentProgress =>
+                return p?.Progress.Map(currentProgress =>
                     p.TotalCount == 0
                         ? 0
                         : (int) (currentProgress * 100 / p.TotalCount)
                 );
             })
             .Switch()
-            .Subscribe(SetCurrentProgress);
+            .Subscribe(async (p, _) => await SetCurrentProgress(p));
 
         Sources = new List<FullName>(sources).AsReadOnly();
         TransportMode = mode;
@@ -75,7 +74,7 @@ public class CopyCommand : CommandBase, ITransportationCommand
 
         recentSpeed
             .Debounce(TimeSpan.FromMilliseconds(500))
-            .Subscribe(SetDisplayDetailLabel);
+            .Subscribe(async (l, _) => await SetDisplayDetailLabel(l));
     }
 
     public override Task<CanCommandRun> CanRun(PointInTime currentTime)
@@ -145,20 +144,21 @@ public class CopyCommand : CommandBase, ITransportationCommand
 
         if (Sources.Count == 1)
         {
-            SetDisplayLabel($"Copy - {Sources[0].GetName()}");
+            await SetDisplayLabelAsync($"Copy - {Sources[0].GetName()}");
         }
         else
         {
             _operationProgresses
                 .Select(o => o.IsDone)
-                .CombineLatest()
-                .Subscribe(statuses =>
+                .CombineAll(statuses =>
                 {
-                    var done = statuses.Count(s => s) + 1;
-                    if (done > statuses.Count) done = statuses.Count;
+                    var statusList = statuses.ToList();
+                    var done = statusList.Count(s => s) + 1;
+                    if (done > statusList.Count) done = statusList.Count;
 
-                    SetDisplayLabel($"Copy - {done} / {statuses.Count}");
-                });
+                    return Task.FromResult($"Copy - {done} / {statusList.Count}");
+                })
+                .Subscribe(async (v, _) => await SetDisplayLabelAsync(v));
         }
     }
 
@@ -196,7 +196,7 @@ public class CopyCommand : CommandBase, ITransportationCommand
                 var newElementPath = target.GetChild(newElementName, AbsolutePathType.Element);
 
                 var currentProgress = _operationProgresses.Find(o => o.Key == element.FullName!.Path);
-                _currentOperationProgress.OnNext(currentProgress);
+                await _currentOperationProgress.SetValue(currentProgress);
 
                 await copyOperation.CopyAsync(new AbsolutePath(_timelessContentProvider, element), newElementPath, new CopyCommandContext(UpdateProgress, currentProgress, _cancellationTokenSource.Token));
             }
diff --git a/src/GuiApp/Avalonia/FileTime.GuiApp.App/Views/MainWindow.axaml b/src/GuiApp/Avalonia/FileTime.GuiApp.App/Views/MainWindow.axaml
index a2ecc99..92ea4bb 100644
--- a/src/GuiApp/Avalonia/FileTime.GuiApp.App/Views/MainWindow.axaml
+++ b/src/GuiApp/Avalonia/FileTime.GuiApp.App/Views/MainWindow.axaml
@@ -21,7 +21,6 @@
     x:DataType="vm:IMainWindowViewModelBase"
     xmlns="https://github.com/avaloniaui"
     xmlns:appCoreModels="using:FileTime.App.Core.Models"
-    xmlns:appInteractions="using:FileTime.App.Core.Interactions"
     xmlns:corevm="using:FileTime.App.Core.ViewModels"
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
     xmlns:i="clr-namespace:Avalonia.Xaml.Interactivity;assembly=Avalonia.Xaml.Interactivity"
@@ -346,7 +345,7 @@
                                                             VerticalAlignment="Top">
                                                             <Grid ColumnDefinitions="*, *" RowDefinitions="Auto, Auto">
                                                                 <Grid ColumnDefinitions="*, Auto" Grid.ColumnSpan="2">
-                                                                    <TextBlock Text="{Binding DisplayLabel^}" />
+                                                                    <TextBlock Text="{Binding DisplayLabel.Value}" />
 
                                                                     <Button Command="{Binding Cancel}" Grid.Column="1">
                                                                         <Image
@@ -362,25 +361,25 @@
                                                                     Grid.Column="0"
                                                                     Grid.Row="1"
                                                                     Margin="0,5,5,5">
-                                                                    <TextBlock Text="{Binding DisplayDetailLabel^}" TextAlignment="Right" />
+                                                                    <TextBlock Text="{Binding DisplayDetailLabel.Value}" TextAlignment="Right" />
 
                                                                     <ProgressBar
                                                                         Margin="0,5,0,0"
                                                                         Maximum="100"
                                                                         MinWidth="50"
-                                                                        Value="{Binding CurrentProgress^}" />
+                                                                        Value="{Binding CurrentProgress.Value}" />
                                                                 </StackPanel>
                                                                 <StackPanel
                                                                     Grid.Column="1"
                                                                     Grid.Row="1"
                                                                     Margin="5,5,0,5">
-                                                                    <TextBlock Text="{Binding TotalProgress^, StringFormat={}{0}%}" TextAlignment="Right" />
+                                                                    <TextBlock Text="{Binding TotalProgress.Value, StringFormat={}{0}%}" TextAlignment="Right" />
 
                                                                     <ProgressBar
                                                                         Margin="0,5,0,0"
                                                                         Maximum="100"
                                                                         MinWidth="50"
-                                                                        Value="{Binding TotalProgress^}" />
+                                                                        Value="{Binding TotalProgress.Value}" />
                                                                 </StackPanel>
                                                             </Grid>
                                                         </Border>
diff --git a/src/Library/DeclarativeProperty/CombineAllProperty.cs b/src/Library/DeclarativeProperty/CombineAllProperty.cs
new file mode 100644
index 0000000..4ee8c0b
--- /dev/null
+++ b/src/Library/DeclarativeProperty/CombineAllProperty.cs
@@ -0,0 +1,36 @@
+namespace DeclarativeProperty;
+
+public class CombineAllProperty<T, TResult> : DeclarativePropertyBase<TResult>
+{
+    private readonly List<IDeclarativeProperty<T>> _sources;
+    private readonly Func<IEnumerable<T>, Task<TResult?>> _combiner;
+
+    public CombineAllProperty(
+        IEnumerable<IDeclarativeProperty<T>> sources,
+        Func<IEnumerable<T>, Task<TResult?>> combiner,
+        Action<TResult?>? setValueHook = null) : base(setValueHook)
+    {
+        var sourcesList = sources.ToList();
+        _sources = sourcesList;
+        _combiner = combiner;
+
+        var initialValueTask = _combiner(sourcesList.Select(p => p.Value));
+        initialValueTask.Wait();
+        SetNewValueSync(initialValueTask.Result);
+
+        foreach (var declarativeProperty in sourcesList)
+        {
+            AddDisposable(declarativeProperty.Subscribe(OnSourceChanged));
+        }
+    }
+
+    private async Task OnSourceChanged(T? arg1, CancellationToken arg2) => await Update();
+
+    private async Task Update()
+    {
+        var values = _sources.Select(p => p.Value);
+        var result = await _combiner(values);
+
+        await SetNewValueAsync(result);
+    }
+}
\ No newline at end of file
diff --git a/src/Library/DeclarativeProperty/DeclarativePropertyExtensions.cs b/src/Library/DeclarativeProperty/DeclarativePropertyExtensions.cs
index 919afd5..e1225ce 100644
--- a/src/Library/DeclarativeProperty/DeclarativePropertyExtensions.cs
+++ b/src/Library/DeclarativeProperty/DeclarativePropertyExtensions.cs
@@ -93,4 +93,10 @@ public static class DeclarativePropertyExtensions
 
     public static IDeclarativeProperty<T> Switch<T>(this IDeclarativeProperty<IDeclarativeProperty<T>?> from)
         => new SwitchProperty<T>(from);
+    
+    public static IDeclarativeProperty<TResult?> CombineAll<T, TResult>(
+        this IEnumerable<IDeclarativeProperty<T>> sources,
+        Func<IEnumerable<T>, Task<TResult>> combiner,
+        Action<TResult?>? setValueHook = null)
+        => new CombineAllProperty<T,TResult?>(sources, combiner, setValueHook);
 }
\ No newline at end of file