diff --git a/src/CodingWithCalvin.LaunchyBar/LaunchyBarPackage.cs b/src/CodingWithCalvin.LaunchyBar/LaunchyBarPackage.cs
index 72abd2a..3bf0976 100644
--- a/src/CodingWithCalvin.LaunchyBar/LaunchyBarPackage.cs
+++ b/src/CodingWithCalvin.LaunchyBar/LaunchyBarPackage.cs
@@ -20,6 +20,7 @@ public sealed class LaunchyBarPackage : AsyncPackage
     private ILaunchService? _launchService;
     private IShellInjectionService? _shellInjectionService;
     private DebugStateService? _debugStateService;
+    private ToolWindowMonitorService? _toolWindowMonitorService;
 
     protected override async Task InitializeAsync(CancellationToken cancellationToken, IProgress<ServiceProgressData> progress)
     {
@@ -59,6 +60,7 @@ protected override async Task InitializeAsync(CancellationToken cancellationToke
                 if (_shellInjectionService.Inject())
                 {
                     _debugStateService = new DebugStateService(this, _configurationService);
+                    _toolWindowMonitorService = new ToolWindowMonitorService(this, _configurationService);
                     break;
                 }
 
@@ -78,6 +80,7 @@ protected override void Dispose(bool disposing)
     {
         if (disposing)
         {
+            _toolWindowMonitorService?.Dispose();
             _debugStateService?.Dispose();
             _shellInjectionService?.Dispose();
             Instance = null;
diff --git a/src/CodingWithCalvin.LaunchyBar/Models/LaunchItem.cs b/src/CodingWithCalvin.LaunchyBar/Models/LaunchItem.cs
index fb3e5a5..1166b6d 100644
--- a/src/CodingWithCalvin.LaunchyBar/Models/LaunchItem.cs
+++ b/src/CodingWithCalvin.LaunchyBar/Models/LaunchItem.cs
@@ -14,6 +14,7 @@ public sealed class LaunchItem : INotifyPropertyChanged
 {
     private string _iconPath = string.Empty;
     private string _name = string.Empty;
+    private bool _isActive;
 
     /// <inheritdoc/>
     public event PropertyChangedEventHandler? PropertyChanged;
@@ -91,6 +92,23 @@ public string IconPath
     /// </summary>
     public bool IsEnabled { get; set; } = true;
 
+    /// <summary>
+    /// Whether this item's tool window is currently visible.
+    /// </summary>
+    [JsonIgnore]
+    public bool IsActive
+    {
+        get => _isActive;
+        set
+        {
+            if (_isActive != value)
+            {
+                _isActive = value;
+                OnPropertyChanged();
+            }
+        }
+    }
+
     /// <summary>
     /// Gets the ImageMoniker for this item's icon.
     /// </summary>
diff --git a/src/CodingWithCalvin.LaunchyBar/Services/ToolWindowMonitorService.cs b/src/CodingWithCalvin.LaunchyBar/Services/ToolWindowMonitorService.cs
new file mode 100644
index 0000000..a3140bb
--- /dev/null
+++ b/src/CodingWithCalvin.LaunchyBar/Services/ToolWindowMonitorService.cs
@@ -0,0 +1,106 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Windows.Threading;
+using CodingWithCalvin.LaunchyBar.Models;
+using Microsoft.VisualStudio.Shell;
+using Microsoft.VisualStudio.Shell.Interop;
+
+namespace CodingWithCalvin.LaunchyBar.Services;
+
+/// <summary>
+/// Monitors tool window visibility and updates IsActive on configured launch items.
+/// </summary>
+public sealed class ToolWindowMonitorService : IDisposable
+{
+    private readonly AsyncPackage _package;
+    private readonly IConfigurationService _configurationService;
+    private readonly DispatcherTimer _timer;
+    private bool _disposed;
+
+    private static readonly Dictionary<string, Guid> ToolWindowGuids = new(StringComparer.OrdinalIgnoreCase)
+    {
+        { "View.SolutionExplorer", new Guid(ToolWindowGuids80.SolutionExplorer) },
+        { "View.Output", new Guid(ToolWindowGuids80.Outputwindow) },
+        { "View.ErrorList", new Guid(ToolWindowGuids80.ErrorList) },
+        { "View.TaskList", new Guid(ToolWindowGuids80.TaskList) },
+        { "View.Toolbox", new Guid(ToolWindowGuids80.Toolbox) },
+        { "View.PropertiesWindow", new Guid(ToolWindowGuids80.PropertiesWindow) },
+        { "View.ClassView", new Guid(ToolWindowGuids80.ClassView) },
+        { "View.Terminal", new Guid("d212f56b-c48a-434c-a121-1c5d80b59b9f") },
+        { "View.GitWindow", new Guid("1c64b9c2-e352-428e-a56d-0ace190b99a6") },
+    };
+
+    public ToolWindowMonitorService(AsyncPackage package, IConfigurationService configurationService)
+    {
+        _package = package;
+        _configurationService = configurationService;
+
+        _timer = new DispatcherTimer
+        {
+            Interval = TimeSpan.FromMilliseconds(500)
+        };
+        _timer.Tick += OnTimerTick;
+        _timer.Start();
+    }
+
+    private void OnTimerTick(object sender, EventArgs e)
+    {
+        ThreadHelper.ThrowIfNotOnUIThread();
+        UpdateActiveStates();
+    }
+
+    private void UpdateActiveStates()
+    {
+        ThreadHelper.ThrowIfNotOnUIThread();
+
+        var shell = _package.GetService<SVsUIShell, IVsUIShell>();
+        if (shell == null) return;
+
+        // Build a set of visible tool window GUIDs
+        var visibleGuids = new HashSet<Guid>();
+        shell.GetToolWindowEnum(out var windowEnum);
+        if (windowEnum != null)
+        {
+            var frames = new IVsWindowFrame[1];
+            while (windowEnum.Next(1, frames, out var fetched) == 0 && fetched == 1)
+            {
+                var frame = frames[0];
+                if (frame == null) continue;
+
+                try
+                {
+                    frame.GetGuidProperty((int)__VSFPROPID.VSFPROPID_GuidPersistenceSlot, out var persistGuid);
+                    frame.IsOnScreen(out var isOnScreen);
+                    if (isOnScreen != 0)
+                    {
+                        visibleGuids.Add(persistGuid);
+                    }
+                }
+                catch
+                {
+                    // Some frames may throw
+                }
+            }
+        }
+
+        // Update IsActive on each configured tool window item
+        foreach (var item in _configurationService.Configuration.Items
+                     .Where(i => i.Type == LaunchItemType.ToolWindow))
+        {
+            if (ToolWindowGuids.TryGetValue(item.Target, out var guid))
+            {
+                item.IsActive = visibleGuids.Contains(guid);
+            }
+        }
+    }
+
+    public void Dispose()
+    {
+        if (_disposed) return;
+        _disposed = true;
+
+        _timer.Stop();
+        _timer.Tick -= OnTimerTick;
+    }
+}
diff --git a/src/CodingWithCalvin.LaunchyBar/UI/LaunchyBarControl.xaml b/src/CodingWithCalvin.LaunchyBar/UI/LaunchyBarControl.xaml
index 6e97207..a3fed0d 100644
--- a/src/CodingWithCalvin.LaunchyBar/UI/LaunchyBarControl.xaml
+++ b/src/CodingWithCalvin.LaunchyBar/UI/LaunchyBarControl.xaml
@@ -10,11 +10,13 @@
              Background="{DynamicResource {x:Static vs:VsBrushes.ToolWindowBackgroundKey}}">
 
   <UserControl.Resources>
+    <BooleanToVisibilityConverter x:Key="BoolToVisibility"/>
+
     <Style x:Key="LaunchyBarButtonStyle" TargetType="Button">
-      <Setter Property="Width" Value="40"/>
+      <Setter Property="Width" Value="44"/>
       <Setter Property="Height" Value="40"/>
-      <Setter Property="Margin" Value="4"/>
-      <Setter Property="Padding" Value="8"/>
+      <Setter Property="Margin" Value="0,4"/>
+      <Setter Property="Padding" Value="0"/>
       <Setter Property="BorderThickness" Value="0"/>
       <Setter Property="Background" Value="Transparent"/>
       <Setter Property="Foreground" Value="{DynamicResource {x:Static vs:VsBrushes.CommandBarTextActiveKey}}"/>
@@ -22,15 +24,31 @@
       <Setter Property="Template">
         <Setter.Value>
           <ControlTemplate TargetType="Button">
-            <Border x:Name="Border"
-                    Background="{TemplateBinding Background}"
-                    BorderBrush="{TemplateBinding BorderBrush}"
-                    BorderThickness="{TemplateBinding BorderThickness}"
-                    CornerRadius="4"
-                    Padding="{TemplateBinding Padding}">
-              <ContentPresenter HorizontalAlignment="Center"
-                                VerticalAlignment="Center"/>
-            </Border>
+            <Grid>
+              <Grid.ColumnDefinitions>
+                <ColumnDefinition Width="3"/>
+                <ColumnDefinition Width="*"/>
+              </Grid.ColumnDefinitions>
+
+              <!-- Active indicator bar on the left edge -->
+              <Rectangle x:Name="ActiveIndicator"
+                         Grid.Column="0"
+                         Fill="{DynamicResource {x:Static vs:VsBrushes.AccentMediumKey}}"
+                         RadiusX="1" RadiusY="1"
+                         Margin="0,6"
+                         Visibility="Collapsed"/>
+
+              <Border x:Name="Border"
+                      Grid.Column="1"
+                      Background="{TemplateBinding Background}"
+                      BorderBrush="{TemplateBinding BorderBrush}"
+                      BorderThickness="{TemplateBinding BorderThickness}"
+                      CornerRadius="4"
+                      Padding="8">
+                <ContentPresenter HorizontalAlignment="Center"
+                                  VerticalAlignment="Center"/>
+              </Border>
+            </Grid>
             <ControlTemplate.Triggers>
               <Trigger Property="IsMouseOver" Value="True">
                 <Setter TargetName="Border" Property="Background"
@@ -43,6 +61,9 @@
               <Trigger Property="IsEnabled" Value="False">
                 <Setter Property="Opacity" Value="0.5"/>
               </Trigger>
+              <DataTrigger Binding="{Binding IsActive}" Value="True">
+                <Setter TargetName="ActiveIndicator" Property="Visibility" Value="Visible"/>
+              </DataTrigger>
             </ControlTemplate.Triggers>
           </ControlTemplate>
         </Setter.Value>