Port floating windows and Message Dialogs

src/AcidicGUI/Layout/LayoutRect.cs

@@ -14,6 +14,7 @@ public struct LayoutRect
 
     public Vector2 TopLeft => new Vector2(Left, Top);
     public Vector2 Size => new Vector2(Width, Height);
+    public Vector2 Center => TopLeft + (Size / 2);
     
     public LayoutRect(float left, float top, float width, float height)
     {

src/AcidicGUI/Rendering/GeometryHelper.cs

@@ -59,6 +59,33 @@ public class GeometryHelper : IFontStashRenderer2
         AddRoundedRectangle(rectangle, uniformRadius, uniformRadius, uniformRadius, uniformRadius, color, texture);
     }
 
+    public void AddQuadOutline(LayoutRect rectangle, float thickness, Color color, Texture2D? texture = null)
+    {
+        float smallerHalf = Math.Min(rectangle.Width, rectangle.Height) / 2;
+        if (smallerHalf <= thickness)
+        {
+            AddQuad(rectangle, color, texture);
+            return;
+        }
+
+        var mesh = GetMeshBuilder(texture);
+
+        var tl = mesh.AddVertex(new Vector2(rectangle.Left, rectangle.Top), color);
+        var tr = mesh.AddVertex(new Vector2(rectangle.Right, rectangle.Top), color);
+        var bl = mesh.AddVertex(new Vector2(rectangle.Left, rectangle.Bottom), color);
+        var br = mesh.AddVertex(new Vector2(rectangle.Right, rectangle.Bottom), color);
+     
+        var tlInner = mesh.AddVertex(new Vector2(rectangle.Left + thickness, rectangle.Top + thickness), color);
+        var trInner = mesh.AddVertex(new Vector2(rectangle.Right - thickness, rectangle.Top + thickness), color);
+        var blInner = mesh.AddVertex(new Vector2(rectangle.Left + thickness, rectangle.Bottom - thickness), color);
+        var brInner = mesh.AddVertex(new Vector2(rectangle.Right - thickness, rectangle.Bottom - thickness), color);
+
+        mesh.AddQuad(tl, tr, tlInner, trInner);
+        mesh.AddQuad(tl, tlInner, bl, blInner);
+        mesh.AddQuad(trInner, tr, brInner, br);
+        mesh.AddQuad(blInner, brInner, bl, br);
+    }
+    
     public void AddQuad(LayoutRect rectangle, Color color, Texture2D? texture = null)
     {
         var mesh = GetMeshBuilder(texture);

src/AcidicGUI/Widgets/Button.cs

@@ -7,9 +7,12 @@ namespace AcidicGUI.Widgets;
 public sealed class Button : 
     ContentWidget,
     IMouseEnterHandler,
+    IMouseClickHandler,
     IMouseLeaveHandler
 {
     private bool hovered;
+
+    public event Action? Clicked;
     
     public void OnMouseEnter(MouseMoveEvent e)
     {
@@ -30,4 +33,13 @@ public sealed class Button :
             geometry.AddQuad(ContentArea, Color.Red);
         }
     }
+
+    public void OnMouseClick(MouseButtonEvent e)
+    {
+        if (e.Button != MouseButton.Left)
+            return;
+
+        e.Handle();
+        Clicked?.Invoke();
+    }
 }

src/AcidicGUI/Widgets/Icon.cs

@@ -6,7 +6,7 @@ namespace AcidicGUI.Widgets;
 
 public sealed class Icon : Widget
 {
-    private Color color = Color.White;
+    private Color? color;
     private string iconString = string.Empty;
     private int iconSize = 24;
 
@@ -30,7 +30,7 @@ public sealed class Icon : Widget
         }
     }
 
-    public Color Color
+    public Color? Color
     {
         get => color;
         set
@@ -59,6 +59,6 @@ public sealed class Icon : Widget
         if (font == null)
             return;
         
-        font.Draw(geometry, new Vector2(x, y), color, iconString, iconSize);
+        font.Draw(geometry, new Vector2(x, y), color ?? Microsoft.Xna.Framework.Color.White, iconString, iconSize);
     }
 }

src/AcidicGUI/Widgets/OverlayWidget.cs

@@ -0,0 +1,6 @@
+namespace AcidicGUI.Widgets;
+
+public sealed class OverlayWidget : ContainerWidget
+{
+    
+}

src/AcidicGUI/Widgets/Widget.Collections.cs

@@ -124,9 +124,15 @@ public partial class Widget
             if (item.Parent != this.parent)
                 throw new InvalidOperationException("The specified widget is not a member of this parent.");
 
-            item.parent = null;
-            this.parent.InvalidateLayout();
-            return children.Remove(item);
+            bool wasSuccess = children.Remove(item);
+
+            if (wasSuccess)
+            {
+                item.parent = null;
+                this.parent.InvalidateLayout();
+            }
+
+            return wasSuccess;
         }
 
         public int Count => children.Count;

src/AcidicGUI/Widgets/Widget.Layout.cs

@@ -201,6 +201,9 @@ public partial class Widget
         
         contentSize.X += margin.Horizontal;
         contentSize.Y += margin.Vertical;
+        contentSize.X += padding.Horizontal;
+        contentSize.Y += padding.Vertical;
+        
         
         if (maximumSize.X > 0)
         {

src/SociallyDistant.Framework/Shell/Common/CompositeIcon.cs

@@ -1,5 +1,6 @@
 #nullable enable
 
+using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Graphics;
 
 namespace SociallyDistant.Core.Shell.Common
@@ -9,7 +10,7 @@ namespace SociallyDistant.Core.Shell.Common
 	{
 		public string textIcon;
 		public Texture2D? spriteIcon;
-		public ShellColor iconColor;
+		public Color? iconColor;
 		
 		public static implicit operator CompositeIcon(string unicodeTextIcon)
 		{
@@ -17,7 +18,7 @@ namespace SociallyDistant.Core.Shell.Common
 			{
 				textIcon = unicodeTextIcon,
 				spriteIcon = null,
-				iconColor = new ShellColor(1, 1, 1, 1)
+				iconColor = null
 			};
 		}
 	}

src/SociallyDistant.Framework/Shell/IShellContext.cs

@@ -2,6 +2,7 @@
 
 using SociallyDistant.Core.Shell.Common;
 using SociallyDistant.Core.Shell.InfoPanel;
+using SociallyDistant.Core.Shell.Windowing;
 
 namespace SociallyDistant.Core.Shell
 {
@@ -15,5 +16,7 @@ namespace SociallyDistant.Core.Shell
 		IInfoPanelService InfoPanelService { get; }
 		
 		Task ShowInfoDialog(string title, string message);
+		
+		IMessageDialog CreateMessageDialog(string title);
 	}
 }

src/SociallyDistant.Framework/Shell/Windowing/IFloatingGui.cs

@@ -3,6 +3,7 @@ using Microsoft.Xna.Framework;
 
 namespace SociallyDistant.Core.Shell.Windowing
 {
+	[Obsolete("IFloatingGui is being replaced with IWindowWithClient<T>.")]
 	public interface IFloatingGui : IWindow, IContentHolder
 	{
 		Vector2 MinimumSize { get; set; }

src/SociallyDistant.Framework/Shell/Windowing/IWindow.cs

@@ -3,12 +3,18 @@ using SociallyDistant.Core.Shell.Common;
 
 namespace SociallyDistant.Core.Shell.Windowing
 {
+	public interface IWindowTab
+	{
+		bool Active { get; }
+		string Title { get; }
+	}
+	
 	public interface IWindow :  ICloseable
 	{
 		public event Action<IWindow>? WindowClosed; 
 
 		WindowHints Hints { get; }
-		IWorkspaceDefinition? Workspace { get; set; }
+		IWorkspaceDefinition Workspace { get; }
 		CompositeIcon Icon { get; set; }
 		
 		bool IsActive { get; }

src/SociallyDistant.Framework/Shell/Windowing/IWorkspaceDefinition.cs

@@ -5,6 +5,5 @@
 		IReadOnlyList < IWindow > WindowList { get; }
 
 		IFloatingGui CreateFloatingGui(string title);
-		IMessageDialog CreateMessageDialog(string title);
 	}
 }

src/SociallyDistant.Framework/UI/Common/DecorativeBlock.cs

@@ -0,0 +1,30 @@
+using Microsoft.Xna.Framework;
+using AcidicGUI.Widgets;
+
+namespace SociallyDistant.Core.UI.Common;
+
+public sealed class DecorativeBlock : Widget
+{
+    private Color? color;
+    private bool opaque;
+
+    public bool Opaque
+    {
+        get => opaque;
+        set
+        {
+            opaque = value;
+            InvalidateGeometry();
+        }
+    }
+
+    public Color? BoxColor
+    {
+        get => color;
+        set
+        {
+            color = value;
+            InvalidateGeometry();
+        }
+    }
+}

src/SociallyDistant.Framework/UI/Common/TextButton.cs

@@ -0,0 +1,36 @@
+using AcidicGUI.Layout;
+using AcidicGUI.Widgets;
+
+namespace SociallyDistant.Core.UI.Common;
+
+public class TextButton : Widget
+{
+    private readonly Button button = new();
+    private readonly TextWidget textWidget = new();
+
+    public Action? ClickCallback { get; set; }
+    
+    public string Text
+    {
+        get => textWidget.Text;
+        set => textWidget.Text = value;
+    }
+    
+    public TextButton()
+    {
+        Children.Add(button);
+        button.Content = textWidget;
+
+        button.Margin = new Padding(15, 0);
+        
+        textWidget.HorizontalAlignment = HorizontalAlignment.Center;
+        textWidget.VerticalAlignment = VerticalAlignment.Middle;
+        
+        button.Clicked += HandleClicked;
+    }
+
+    private void HandleClicked()
+    {
+        ClickCallback?.Invoke();
+    }
+}

src/SociallyDistant.Framework/UI/VisualStyles/SociallyDistantVisualStyle.cs

@@ -6,6 +6,8 @@ using AcidicGUI.Widgets;
 using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Graphics;
 using SociallyDistant.Core.Modules;
+using SociallyDistant.Core.Shell.Windowing;
+using SociallyDistant.Core.UI.Common;
 
 namespace SociallyDistant.Core.UI.VisualStyles;
 
@@ -14,7 +16,16 @@ public class SociallyDistantVisualStyle : IVisualStyle
     private readonly IGameContext game;
     private readonly Color mainBackground = new Color(0x11, 0x13, 0x15);
     private readonly Color statusBarColor = new Color(0x01,0x22, 0x37, 0xff);
+    private readonly Color accentPrimary = new Color(0x13, 0x85, 0xC3, 0xff);
 
+    // Tabs - Inactive
+    private readonly Color tabInactiveBackgroundDefault = new Color(0x44, 0x44, 0x44, 191);
+    private readonly Color tabInactiveBorderDefault = new Color(0x44, 0x44, 0x44);
+    
+    // Tabs - Active
+    private readonly Color tabActiveBackgroundDefault = new Color(0x16, 0x93, 0xD6, 190);
+    private readonly Color tabActiveBorderDefault = new Color(0x16, 0x93, 0xD6);
+    
     private Font iconFont;
     private Font defaultFont = null!;
 
@@ -79,11 +90,78 @@ public class SociallyDistantVisualStyle : IVisualStyle
             }
         }
     }
+
+    private void DrawWindowTab(Widget widget, IWindowTab tab, GeometryHelper geometry)
+    {
+        var thickness = 1;
+        var background = tabInactiveBackgroundDefault;
+        var border = tabInactiveBorderDefault;
+
+        if (tab.Active)
+        {
+            background = tabActiveBackgroundDefault;
+            border = tabActiveBorderDefault;
+        }
+
+        geometry.AddRoundedRectangle(
+            widget.ContentArea,
+            3,
+            3,
+            0,
+            0,
+            background
+        );
+        
+        geometry.AddRoundedRectangleOutline(
+            widget.ContentArea,
+            thickness,
+            3,
+            3,
+            0,
+            0,
+            border
+        );
+    }
+
+    private void DrawDecorativeBlock(DecorativeBlock widget, GeometryHelper geometry)
+    {
+        var color = (widget.BoxColor ?? accentPrimary);
+
+        if (widget.Opaque)
+        {
+            geometry.AddRoundedRectangle(
+                widget.ContentArea,
+                3,
+                color
+            );
+        }
+        else
+        {
+            geometry.AddRoundedRectangle(
+                widget.ContentArea,
+                3,
+                color * 0.5f
+            );
+
+            geometry.AddRoundedRectangleOutline(
+                widget.ContentArea,
+                2,
+                3,
+                color
+            );
+
+
+        }
+    }
     
     public void DrawWidgetBackground(Widget widget, GeometryHelper geometryHelper)
     {
         if (widget is InputField inputField)
             DrawInputField(inputField, geometryHelper);
+        else if (widget is IWindowTab tab)
+            DrawWindowTab(widget, tab, geometryHelper);
+        else if (widget is DecorativeBlock box)
+            DrawDecorativeBlock(box, geometryHelper);
         else
         {
             WidgetBackgrounds background = widget.GetCustomProperty<WidgetBackgrounds>();
@@ -93,9 +171,18 @@ public class SociallyDistantVisualStyle : IVisualStyle
                 case WidgetBackgrounds.StatusBar:
                     DrawStatusBar(widget, geometryHelper);
                     break;
+                case WidgetBackgrounds.Overlay:
+                    geometryHelper.AddQuad(widget.ContentArea, mainBackground * 0.67f);
+                    break;
                 case WidgetBackgrounds.Dock:
                     DrawDock(widget, geometryHelper);
                     break;
+                case WidgetBackgrounds.WindowClient:
+                    geometryHelper.AddQuad(widget.ContentArea, mainBackground);
+                    break;
+                case WidgetBackgrounds.WindowBorder:
+                    geometryHelper.AddQuadOutline(widget.ContentArea, 1, accentPrimary);
+                    break;
             }
         }
     }
@@ -139,6 +226,9 @@ public enum InputFieldStyle
 public enum WidgetBackgrounds
 {
     None,
+    Overlay,
     StatusBar,
-    Dock
+    Dock,
+    WindowClient,
+    WindowBorder,
 }

src/SociallyDistant/UI/Common/CompositeIconWidget.cs

@@ -0,0 +1,55 @@
+using AcidicGUI.Widgets;
+using Microsoft.Xna.Framework;
+using SociallyDistant.Core.Shell.Common;
+
+namespace SociallyDistant.UI.Common;
+
+public class CompositeIconWidget : Widget
+{
+    private readonly Image image = new();
+    private readonly Icon textIcon = new();
+    
+    private CompositeIcon compositeIcon;
+    private int iconSize = 24;
+
+    public int IconSize
+    {
+        get => iconSize;
+        set
+        {
+            iconSize = value;
+            UpdateIconSize();
+        }
+    }
+
+    public CompositeIcon Icon
+    {
+        get => compositeIcon;
+        set
+        {
+            compositeIcon = value;
+            UpdateIcon();
+        }
+    }
+
+    private void UpdateIconSize()
+    {
+        image.MaximumSize = new Vector2(iconSize, iconSize);
+        image.MinimumSize = image.MaximumSize;
+        textIcon.IconSize = iconSize;
+    }
+
+    public CompositeIconWidget()
+    {
+        Children.Add(image);
+        Children.Add(textIcon);
+    }
+    
+    private void UpdateIcon()
+    {
+        image.Texture = compositeIcon.spriteIcon;
+        textIcon.IconString = compositeIcon.textIcon;
+
+        textIcon.Color = compositeIcon.iconColor;
+    }
+}

src/SociallyDistant/UI/Common/InfoBox.cs

@@ -0,0 +1,46 @@
+using AcidicGUI.Layout;
+using AcidicGUI.Widgets;
+using Microsoft.Xna.Framework;
+using SociallyDistant.Core.UI.Common;
+
+namespace SociallyDistant.UI.Common;
+
+public sealed class InfoBox : Widget
+{
+    private readonly StackPanel root = new();
+    private readonly DecorativeBlock decorativeBlock = new();
+    private readonly StackPanel contentStack = new();
+    private readonly TextWidget title = new();
+    private readonly Box contentBox = new();
+
+    public string TitleText
+    {
+        get => title.Text;
+        set => title.Text = value;
+    }
+    
+    public Widget? Content
+    {
+        get => contentBox.Content;
+        set => contentBox.Content = value;
+    }
+
+    public InfoBox()
+    {
+        Children.Add(root);
+        root.ChildWidgets.Add(decorativeBlock);
+        root.ChildWidgets.Add(contentStack);
+        contentStack.ChildWidgets.Add(title);
+        contentStack.ChildWidgets.Add(contentBox);
+
+        root.Padding = 3;
+        root.Spacing = 3;
+        root.Direction = Direction.Horizontal;
+
+        contentStack.Spacing = 3;
+        contentStack.Padding = new Padding(0, 3);
+        contentStack.Direction = Direction.Vertical;
+
+        decorativeBlock.MinimumSize = new Vector2(18, 0);
+    }
+}

src/SociallyDistant/UI/Common/MessageDalog.cs

@@ -0,0 +1,219 @@
+using System.Collections;
+using AcidicGUI.Layout;
+using AcidicGUI.Widgets;
+using SociallyDistant.Core.Shell;
+using SociallyDistant.Core.Shell.Common;
+using SociallyDistant.Core.Shell.Windowing;
+using SociallyDistant.Core.UI.Common;
+using SociallyDistant.UI.Windowing;
+
+namespace SociallyDistant.UI.Common;
+
+public sealed class MessageDialog : IMessageDialog
+{
+    private readonly Window window;
+    private readonly InfoBox infoBox = new();
+    private readonly StackPanel contentStack = new();
+    private readonly TextWidget message = new();
+    private readonly WrapPanel buttonsPanel = new();
+    private readonly ButtonList buttonList;
+    private readonly List<TextButton> views = new();
+
+    private MessageDialogResult dismissResult = MessageDialogResult.Cancel;
+    
+    public MessageDialog(Window window)
+    {
+        buttonList = new ButtonList(this);
+        
+        this.window = window;
+        this.window.SetClient(infoBox);
+
+        infoBox.Content = contentStack;
+        contentStack.ChildWidgets.Add(message);
+        contentStack.ChildWidgets.Add(buttonsPanel);
+
+        contentStack.Spacing = 6;
+        buttonsPanel.SpacingX = 3;
+        buttonsPanel.SpacingY = 3;
+        buttonsPanel.Direction = Direction.Horizontal;
+    }
+
+    public bool CanClose
+    {
+        get => window.CanClose;
+        set => window.CanClose = value;
+    }
+    
+    public void Close()
+    {
+        DismissCallback?.Invoke(dismissResult);
+        window.ForceClose();
+    }
+
+    public void ForceClose()
+    {
+        Close();
+    }
+
+    public event Action<IWindow>? WindowClosed
+    {
+        add
+        {
+            window.WindowClosed += value;
+        }
+        remove
+        {
+            window.WindowClosed -= value;
+        }
+    }
+
+    public WindowHints Hints => window.Hints;
+    public IWorkspaceDefinition Workspace => window.Workspace;
+
+    public CompositeIcon Icon
+    {
+        get => window.Icon;
+        set => window.Icon = value;
+    }
+
+    public bool IsActive => window.IsActive;
+    public IWorkspaceDefinition CreateWindowOverlay()
+    {
+        return window.CreateWindowOverlay();
+    }
+
+    public void SetWindowHints(WindowHints hints)
+    {
+        window.SetWindowHints(hints);
+    }
+
+    public string Title
+    {
+        get => infoBox.TitleText;
+        set => infoBox.TitleText = value;
+    }
+
+    public string Message
+    {
+        get => message.Text;
+        set => message.Text = value;
+    }
+    public CommonColor Color { get; set; }
+    public MessageBoxType MessageType { get; set; }
+    public IList<MessageBoxButtonData> Buttons => buttonList;
+    public Action<MessageDialogResult>? DismissCallback { get; set; }
+
+    private void Dismiss(MessageDialogResult result)
+    {
+        dismissResult = result;
+        Close();
+    }
+    
+    private void RefreshButtons()
+    {
+        while (views.Count > buttonList.Count)
+        {
+            buttonsPanel.ChildWidgets.Remove(views[^1]);
+            views.RemoveAt(views.Count-1);
+        }
+
+        while (views.Count < buttonList.Count)
+        {
+            var button = new TextButton();
+            views.Add(button);
+            buttonsPanel.ChildWidgets.Add(button);
+        }
+
+        for (var i = 0; i < buttonList.Count; i++)
+        {
+            var button = buttonList[i];
+            var view = views[i];
+
+            view.Text = button.Text;
+            view.ClickCallback = () =>
+            {
+                Dismiss(button.Result);
+            };
+        }
+    }
+    
+    private class ButtonList : IList<MessageBoxButtonData>
+    {
+        private readonly MessageDialog dialog;
+        private readonly List<MessageBoxButtonData> data = new();
+
+        public ButtonList(MessageDialog dialog)
+        {
+            this.dialog = dialog;
+        }
+        
+        public IEnumerator<MessageBoxButtonData> GetEnumerator()
+        {
+            return data.GetEnumerator();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return GetEnumerator();
+        }
+
+        public void Add(MessageBoxButtonData item)
+        {
+            data.Add(item);
+            dialog.RefreshButtons();
+        }
+
+        public void Clear()
+        {
+            data.Clear();
+            dialog.RefreshButtons();
+        }
+
+        public bool Contains(MessageBoxButtonData item)
+        {
+            return data.Contains(item);
+        }
+
+        public void CopyTo(MessageBoxButtonData[] array, int arrayIndex)
+        {
+            data.CopyTo(array, arrayIndex);
+        }
+
+        public bool Remove(MessageBoxButtonData item)
+        {
+            bool result = data.Remove(item);
+            if (result)
+                dialog.RefreshButtons();
+            return result;
+        }
+
+        public int Count => data.Count;
+        public bool IsReadOnly => false;
+        public int IndexOf(MessageBoxButtonData item)
+        {
+            return data.IndexOf(item);
+        }
+
+        public void Insert(int index, MessageBoxButtonData item)
+        {
+            data.Insert(index, item);
+            dialog.RefreshButtons();
+        }
+
+        public void RemoveAt(int index)
+        {
+            data.RemoveAt(index);
+            dialog.RefreshButtons();
+        }
+
+        public MessageBoxButtonData this[int index]
+        {
+            get => data[index];
+            set
+            {
+                data[index] = value;
+                dialog.RefreshButtons();
+            }
+        }
+    }
+}

src/SociallyDistant/UI/GuiController.cs

@@ -1,19 +1,23 @@
+using System.Text;
 using AcidicGUI.CustomProperties;
 using AcidicGUI.Layout;
 using AcidicGUI.Widgets;
 using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Graphics;
+using Serilog;
 using SociallyDistant.Core.Core;
 using SociallyDistant.Core.Modules;
 using SociallyDistant.Core.OS.Devices;
 using SociallyDistant.Core.Shell;
 using SociallyDistant.Core.Shell.Common;
 using SociallyDistant.Core.Shell.InfoPanel;
+using SociallyDistant.Core.Shell.Windowing;
 using SociallyDistant.Core.UI;
 using SociallyDistant.Player;
 using SociallyDistant.UI.Common;
 using SociallyDistant.UI.InfoWidgets;
 using SociallyDistant.UI.Shell;
+using SociallyDistant.UI.Windowing;
 
 namespace SociallyDistant.UI;
 
@@ -25,7 +29,9 @@ public class GuiController :
     private readonly InfoPanelController infoPanel = new();
     private readonly FlexPanel mainPanel = new();
     private readonly StatusBar statusBar = new();
+    private readonly OverlayWidget workArea = new();
     private readonly Box mainBox = new();
+    private readonly FloatingWorkspace floatingWindowArea = new();
     private readonly GuiService guiService;
     private readonly PlayerManager playerManager;
     private readonly DesktopController desktopController;
@@ -48,14 +54,37 @@ public class GuiController :
         guiService.GuiRoot.TopLevels.Add(mainPanel);
 
         mainPanel.ChildWidgets.Add(statusBar);
-        mainPanel.ChildWidgets.Add(mainBox);
+        mainPanel.ChildWidgets.Add(workArea);
 
-        mainBox.GetCustomProperties<FlexPanelProperties>().Mode = FlexMode.Proportional;
+        workArea.ChildWidgets.Add(mainBox);
+        workArea.ChildWidgets.Add(floatingWindowArea);
+        
+        workArea.GetCustomProperties<FlexPanelProperties>().Mode = FlexMode.Proportional;
     }
 
-    public async Task ShowExceptionMessage(Exception ex)
+    public Task ShowExceptionMessage(Exception ex)
     {
-        // TODO
+        var dialog = CreateMessageDialog("System Error");
+        var completionSource = new TaskCompletionSource<MessageDialogResult>();
+
+        var messageBuilder = new StringBuilder();
+
+        messageBuilder.AppendLine("Socially Distant has encountered an unexpected problem.");
+        messageBuilder.AppendLine();
+        messageBuilder.AppendLine("<b>What happened?</b>");
+        messageBuilder.AppendLine(
+            $"An unhandled .NET runtime exception ({ex.GetType().FullName}) occurred. {ex.Message}");
+
+        messageBuilder.AppendLine();
+        messageBuilder.AppendLine(
+            "This generally happens as a result of a broken mod or a bug in the game. Details have been logged to the game's log.");
+        
+        Log.Error(ex.ToString());
+
+        dialog.Message = messageBuilder.ToString();
+        dialog.Buttons.Add("OK");
+        
+        return completionSource.Task;
     }
 
     private void OnGameModeChanged(GameMode gameMode)
@@ -64,7 +93,7 @@ public class GuiController :
         {
             this.desktop = new Desktop(desktopController);
             this.mainBox.Content = desktop;
-
+            
             desktopController.Login();
         }
         else
@@ -76,9 +105,41 @@ public class GuiController :
     public INotificationManager NotificationManager => notificationManager;
     public IInfoPanelService InfoPanelService => infoPanel;
 
-    public async Task ShowInfoDialog(string title, string message)
+    public Task ShowInfoDialog(string title, string message)
     {
-        // TODO
+        var completionSource = new TaskCompletionSource<MessageDialogResult>();
+        var dialog = CreateMessageDialog(title);
+
+        dialog.Message = message;
+        dialog.DismissCallback = completionSource.SetResult;
+        dialog.Buttons.Add("OK");
+
+        return completionSource.Task;
+    }
+
+    private OverlayWorkspace CreateOverlayWorkspace()
+    {
+        var workspace = new OverlayWorkspace();
+        this.workArea.ChildWidgets.Add(workspace);
+        return workspace;
+    }
+    
+    public IMessageDialog CreateMessageDialog(string title)
+    {
+        var overlay = CreateOverlayWorkspace();
+        var window = overlay.CreateWindow(title);
+        var dialog = new MessageDialog(window);
+
+        dialog.Title = title;
+        
+        dialog.WindowClosed += HandleDialogClosed;
+
+        return dialog;
+        
+        void HandleDialogClosed(IWindow obj)
+        {
+            workArea.ChildWidgets.Remove(overlay);
+        }
     }
 }
 

src/SociallyDistant/UI/Windowing/FloatingWorkspace.cs

@@ -0,0 +1,138 @@
+using AcidicGUI;
+using AcidicGUI.CustomProperties;
+using AcidicGUI.Layout;
+using AcidicGUI.Widgets;
+using Microsoft.Xna.Framework;
+using SociallyDistant.Core.Shell.Windowing;
+using SociallyDistant.Core.UI.VisualStyles;
+
+namespace SociallyDistant.UI.Windowing;
+
+public class OverlayWorkspace :
+    Widget,
+    IClientWorkspaceDefinition<Window, Widget?>
+{
+    private readonly FloatingWorkspace workspace = new();
+
+    public OverlayWorkspace()
+    {
+        Children.Add(workspace);
+        this.SetCustomProperty(WidgetBackgrounds.Overlay);
+    }
+    
+    public Window CreateWindow(string title, Widget? client = default)
+    {
+        return workspace.CreateWindow(title, client);
+    }
+
+    public IReadOnlyList<IWindow> WindowList => workspace.WindowList;
+    public IFloatingGui CreateFloatingGui(string title)
+    {
+        throw new NotImplementedException();
+    }
+}
+
+public class FloatingWorkspace :
+    Widget,
+    IClientWorkspaceDefinition<Window, Widget?>,
+    INotifyCloseWorkspace
+{
+    private readonly List<WindowBase> windows = new();
+
+    public FloatingWorkspace()
+    {
+        LayoutRoot = this;
+    }
+    
+    public Window CreateWindow(string title, Widget? client = default)
+    {
+        var win = new Window(this);
+
+        win.SetClient(client);
+        
+        this.Children.Add(win);
+        windows.Add(win);
+
+        return win;
+    }
+
+    public void OnCloseWindow(WindowBase window)
+    {
+        windows.Remove(window);
+        Children.Remove(window);
+    }
+
+    public IReadOnlyList<IWindow> WindowList => windows;
+    public IFloatingGui CreateFloatingGui(string title)
+    {
+        throw new NotImplementedException();
+    }
+
+    public IMessageDialog CreateMessageDialog(string title)
+    {
+        throw new NotImplementedException();
+    }
+
+    protected override Vector2 GetContentSize(Vector2 availableSize)
+    {
+        return availableSize;
+    }
+
+    protected override void ArrangeChildren(IGuiContext context, LayoutRect availableSpace)
+    {
+        foreach (Widget win in Children)
+        {
+            var childSize = win.GetCachedContentSize(availableSpace.Size);
+            var windowSettings = win.GetCustomProperties<WindowSettings>();
+
+            if (windowSettings.Maximized)
+            {
+                win.UpdateLayout(context, availableSpace);
+            }
+            else
+            {
+                var positionInWorkspace = availableSpace.Center + windowSettings.Position;
+                var layoutPosition = positionInWorkspace - (childSize / 2);
+
+                win.UpdateLayout(context, new LayoutRect(
+                    layoutPosition.X,
+                    layoutPosition.Y,
+                    childSize.X,
+                    childSize.Y
+                ));
+            }
+
+
+        }
+    }
+}
+
+public sealed class WindowSettings : CustomPropertyObject
+{
+    private Vector2 position;
+    private bool maximized;
+
+    public bool Maximized
+    {
+        get => maximized;
+        set
+        {
+            maximized = value;
+            Widget.InvalidateLayout();
+        }
+    }
+    
+    public Vector2 Position
+    {
+        get => position;
+        set
+        {
+            position = value;
+            Widget.InvalidateLayout();
+        }
+    }
+
+    public WindowSettings(Widget owner) : base(owner)
+    {
+    }
+}

src/SociallyDistant/UI/Windowing/INotifyCloseWorkspace.cs

@@ -0,0 +1,9 @@
+using AcidicGUI.Widgets;
+using SociallyDistant.Core.Shell.Windowing;
+
+namespace SociallyDistant.UI.Windowing;
+
+internal interface INotifyCloseWorkspace : IWorkspaceDefinition
+{
+    void OnCloseWindow(WindowBase window);
+}

src/SociallyDistant/UI/Windowing/Window.cs

@@ -0,0 +1,23 @@
+using AcidicGUI.Widgets;
+using SociallyDistant.Core.Shell.Windowing;
+
+namespace SociallyDistant.UI.Windowing;
+
+public sealed class Window :
+    WindowBase,
+    IWindowWithClient<Widget?>
+{
+    private readonly ITabDefinition tab;
+    
+    internal Window(INotifyCloseWorkspace workspace) : base(workspace)
+    {
+        tab = Tabs.CreateTab();
+        tab.Active = true;
+    }
+
+    public Widget? Client => Decorations.Client;
+    public void SetClient(Widget? newClient)
+    {
+        Decorations.Client = newClient;
+    }
+}

src/SociallyDistant/UI/Windowing/WindowBase.cs

@@ -0,0 +1,58 @@
+using AcidicGUI.Widgets;
+using SociallyDistant.Core.Shell.Common;
+using SociallyDistant.Core.Shell.Windowing;
+
+namespace SociallyDistant.UI.Windowing;
+
+public abstract class WindowBase : 
+    Widget, 
+    IWindow
+{
+    private readonly INotifyCloseWorkspace workspace;
+    private readonly WindowDecoration decoration;
+    
+    public bool CanClose { get; set; }
+
+    protected WindowDecoration Decorations => decoration;
+    protected WindowTabList Tabs => decoration.Tabs;
+    
+    internal WindowBase(INotifyCloseWorkspace workspace)
+    {
+        decoration = new WindowDecoration(this);
+        
+        this.workspace = workspace;
+
+        Children.Add(decoration);
+    }
+    
+    public void Close()
+    {
+        throw new NotImplementedException();
+    }
+
+    public void ForceClose()
+    {
+        workspace.OnCloseWindow(this);
+        WindowClosed?.Invoke(this);
+    }
+
+    public CompositeIcon Icon
+    {
+        get => decoration.Icon;
+        set => decoration.Icon = value;
+    }
+
+    public event Action<IWindow>? WindowClosed;
+    public WindowHints Hints => decoration.Hints;
+    public IWorkspaceDefinition Workspace => workspace;
+    public bool IsActive => IsChildFocused;
+    public IWorkspaceDefinition CreateWindowOverlay()
+    {
+        throw new NotImplementedException();
+    }
+
+    public void SetWindowHints(WindowHints hints)
+    {
+        throw new NotImplementedException();
+    }
+}

src/SociallyDistant/UI/Windowing/WindowDecoration.cs

@@ -0,0 +1,87 @@
+using AcidicGUI.CustomProperties;
+using AcidicGUI.Layout;
+using AcidicGUI.Widgets;
+using Microsoft.Xna.Framework;
+using SociallyDistant.Core.Shell;
+using SociallyDistant.Core.Shell.Common;
+using SociallyDistant.Core.Shell.Windowing;
+using SociallyDistant.Core.UI.VisualStyles;
+using SociallyDistant.UI.Common;
+
+namespace SociallyDistant.UI.Windowing;
+
+public class WindowDecoration : Widget
+{
+    private readonly FlexPanel flexPanel = new();
+    private readonly FlexPanel titleBar = new();
+    private readonly Box borderBox = new();
+    private readonly Box clientBox = new();
+    private readonly WindowBase window;
+    private readonly WindowDragSurface dragSurface;
+    private readonly CompositeIconWidget titleIcon = new();
+    private readonly WindowTabList tabList = new();
+    
+    private WindowHints hints;
+
+    public WindowHints Hints => hints;
+
+    public CompositeIcon Icon
+    {
+        get => titleIcon.Icon;
+        set => titleIcon.Icon = value;
+    }
+    
+    public Widget? Client
+    {
+        get => clientBox.Content;
+        set => clientBox.Content = value;
+    }
+
+    public WindowTabList Tabs => tabList;
+    
+    public WindowDecoration(WindowBase window)
+    {
+        this.window = window;
+        this.dragSurface = new WindowDragSurface((window));
+
+        Children.Add(flexPanel);
+
+        flexPanel.ChildWidgets.Add(dragSurface);
+        flexPanel.ChildWidgets.Add(borderBox);
+
+        dragSurface.Content = titleBar;
+
+        titleBar.Direction = Direction.Horizontal;
+        titleBar.Padding = new Padding(3, 0);
+        titleBar.Spacing = 3;
+
+        titleBar.ChildWidgets.Add(titleIcon);
+        titleBar.ChildWidgets.Add(tabList);
+
+        tabList.GetCustomProperties<FlexPanelProperties>().Mode = FlexMode.Proportional;
+        
+        borderBox.Margin = 1;
+        borderBox.Content = clientBox;
+
+        titleIcon.VerticalAlignment = VerticalAlignment.Bottom;
+        titleIcon.Padding = new Padding(0, 3);
+        
+        borderBox.SetCustomProperty(WidgetBackgrounds.WindowBorder);
+        clientBox.SetCustomProperty(WidgetBackgrounds.WindowClient);
+        clientBox.GetCustomProperties<FlexPanelProperties>().Mode = FlexMode.Proportional;
+
+        tabList.VerticalAlignment = VerticalAlignment.Bottom;
+        
+        Icon = new CompositeIcon()
+        {
+            textIcon = MaterialIcons.Window
+        };
+    }
+}
+
+public interface ITabDefinition
+{
+    string Title { get; set; }
+    bool Closeable { get; set; }
+    bool Active { get; set; }
+}

src/SociallyDistant/UI/Windowing/WindowDragSurface.cs

@@ -0,0 +1,57 @@
+using AcidicGUI.Events;
+using AcidicGUI.Widgets;
+using Microsoft.Xna.Framework;
+
+namespace SociallyDistant.UI.Windowing;
+
+public sealed class WindowDragSurface : 
+    ContentWidget,
+    IDragStartHandler,
+    IDragHandler,
+    IDragEndHandler
+{
+    private readonly WindowBase window;
+
+    private bool dragging;
+    
+    public WindowDragSurface(WindowBase window)
+    {
+        MinimumSize = new Vector2(0, 24);
+        this.window = window;
+    }
+    
+    public void OnDragStart(MouseButtonEvent e)
+    {
+        if (e.Button != MouseButton.Left)
+            return;
+
+        e.RequestFocus();
+        dragging = true;
+    }
+
+    public void OnDrag(MouseButtonEvent e)
+    {
+        if (!dragging)
+            return;
+
+        var settings = window.GetCustomProperties<WindowSettings>();
+
+        if (settings.Maximized)
+            return;
+
+        settings.Position += e.Movement;
+
+        e.RequestFocus();
+    }
+
+    public void OnDragEnd(MouseButtonEvent e)
+    {
+        if (!dragging)
+            return;
+
+        if (e.Button != MouseButton.Left)
+            return;
+
+        dragging = false;
+    }
+}

src/SociallyDistant/UI/Windowing/WindowTab.cs

@@ -0,0 +1,49 @@
+using AcidicGUI.Layout;
+using AcidicGUI.Widgets;
+using SociallyDistant.Core.Shell;
+using SociallyDistant.Core.Shell.Windowing;
+
+namespace SociallyDistant.UI.Windowing;
+
+public sealed class WindowTab : 
+    Widget, 
+    IWindowTab
+{
+    private readonly StackPanel stackPanel = new();
+    private readonly TextWidget titleText = new();
+    private readonly Button closeButton = new();
+    private readonly Icon closeIcon = new();
+
+    private bool active = false;
+
+    public string Title
+    {
+        get => titleText.Text;
+        set => titleText.Text = value;
+    }
+
+    public bool Active
+    {
+        get => active;
+        set
+        {
+            active = value;
+            InvalidateGeometry();
+        }
+    }
+    
+    public WindowTab()
+    {
+        Children.Add(stackPanel);
+        stackPanel.ChildWidgets.Add(titleText);
+        stackPanel.ChildWidgets.Add(closeButton);
+        closeButton.Content = closeIcon;
+
+        closeIcon.IconSize = 18;
+        closeIcon.IconString = MaterialIcons.Close;
+
+        stackPanel.Direction = Direction.Horizontal;
+        stackPanel.Spacing = 3;
+        stackPanel.Margin = 3;
+    }
+}

src/SociallyDistant/UI/Windowing/WindowTabList.cs

@@ -0,0 +1,109 @@
+using AcidicGUI.Layout;
+using AcidicGUI.Widgets;
+using SociallyDistant.Core.Shell.Windowing;
+
+namespace SociallyDistant.UI.Windowing;
+
+public sealed class WindowTabList : Widget
+{
+    private readonly WrapPanel wrapPanel = new();
+    private readonly List<WindowTab> views = new();
+    private readonly List<Definition> definitions = new();
+
+    private bool showNewTab = false;
+    
+    public WindowTabList()
+    {
+        Children.Add(wrapPanel);
+
+        wrapPanel.Direction = Direction.Horizontal;
+    }
+
+    public ITabDefinition CreateTab()
+    {
+        var definition = new Definition(this);
+
+        definitions.Add(definition);
+        
+        UpdateViews();
+        
+        return definition;
+    }
+
+    public void RemoveTab(ITabDefinition definition)
+    {
+        if (definition is not Definition actualDefinition)
+            return;
+
+        definitions.Remove(actualDefinition);
+        UpdateViews();
+    }
+    
+    private void UpdateViews()
+    {
+        while (views.Count > definitions.Count)
+        {
+            wrapPanel.ChildWidgets.Remove(views[^1]);
+            views.RemoveAt(views.Count-1);
+        }
+
+        while (views.Count < definitions.Count)
+        {
+            var view = new WindowTab();
+            views.Add(view);
+            wrapPanel.ChildWidgets.Add(view);
+        }
+
+        for (var i = 0; i < definitions.Count; i++)
+        {
+            Definition definition = definitions[i];
+            WindowTab view = views[i];
+
+            view.Title = definition.Title;
+            view.Active = definition.Active;
+        }
+    }
+    
+    internal class Definition : ITabDefinition
+    {
+        private readonly WindowTabList list;
+        private string title = "Tab title";
+        private bool closeable;
+        private bool active;
+
+        public Definition(WindowTabList list)
+        {
+            this.list = list;
+        }
+
+        public string Title
+        {
+            get => title;
+            set
+            {
+                title = value;
+                list.UpdateViews();
+            }
+        }
+
+        public bool Closeable
+        {
+            get => closeable;
+            set
+            {
+                closeable = value;
+                list.UpdateViews();
+            }
+        }
+
+        public bool Active
+        {
+            get => active;
+            set
+            {
+                active = value;
+                list.UpdateViews();
+            }
+        }
+    }
+}