Add per-screen layouts with DPI-aware widget positioning and an empty layout option

src/DesktopMagic/DataContexts/MainWindowDataContext.cs

@@ -1,7 +1,10 @@
 using DesktopMagic.Helpers;
 using DesktopMagic.Settings;
 
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.ComponentModel;
+using System.Linq;
 using System.Runtime.CompilerServices;
 
 namespace DesktopMagic.DataContexts;
@@ -11,6 +14,8 @@ internal class MainWindowDataContext : INotifyPropertyChanged
     public event PropertyChangedEventHandler? PropertyChanged;
 
     private static DesktopMagicSettings settings = new();
+    private static string? selectedScreenDeviceName;
+    private string? selectedLayoutName;
 
     private bool isLoading = true;
     private string? pluginsSearchText;
@@ -34,6 +39,30 @@ internal class MainWindowDataContext : INotifyPropertyChanged
         }
     }
 
+    public ObservableCollection<ScreenDisplay> Screens { get; } = [];
+
+    public string? SelectedScreenId
+    {
+        get => selectedScreenDeviceName;
+        set
+        {
+            selectedScreenDeviceName = value;
+            UpdateSelection();
+        }
+    }
+
+    public Layout SelectedLayout => Manager.Instance.SelectedLayout;
+
+    public string? SelectedLayoutName
+    {
+        get => selectedLayoutName;
+        set
+        {
+            selectedLayoutName = value;
+            OnPropertyChanged();
+        }
+    }
+
     public bool IsLoading
     {
         get => isLoading;
@@ -76,8 +105,67 @@ internal class MainWindowDataContext : INotifyPropertyChanged
         return settings;
     }
 
+    /// <summary>
+    /// Refreshes the list of detected screens and ensures a screen is selected.
+    /// </summary>
+    public void RefreshScreens()
+    {
+        List<System.Windows.Forms.Screen> allScreens = ScreenUtilities.GetAllScreens();
+
+        Screens.Clear();
+        for (int i = 0; i < allScreens.Count; i++)
+        {
+            Screens.Add(new ScreenDisplay(allScreens[i], i));
+        }
+
+        if (selectedScreenDeviceName is null || !Screens.Any(screen => screen.DeviceName == selectedScreenDeviceName))
+        {
+            SelectedScreenId = Screens.FirstOrDefault()?.DeviceName;
+        }
+        else
+        {
+            UpdateSelection();
+        }
+    }
+
+    /// <summary>
+    /// Raises change notifications for the currently selected screen's layout.
+    /// </summary>
+    public void RefreshSelection()
+    {
+        UpdateSelection();
+    }
+
+    /// <summary>
+    /// Keeps the manager's screen selection in sync and raises notifications for the selected layout.
+    /// </summary>
+    private void UpdateSelection()
+    {
+        Manager.Instance.SelectedScreenDeviceName = selectedScreenDeviceName;
+        selectedLayoutName = Manager.Instance.SelectedLayout.Name;
+        OnPropertyChanged(nameof(SelectedScreenId));
+        OnPropertyChanged(nameof(SelectedLayout));
+        OnPropertyChanged(nameof(SelectedLayoutName));
+    }
+
     protected void OnPropertyChanged([CallerMemberName] string? name = null)
     {
         PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
     }
 }
+
+/// <summary>
+/// A detected screen displayed in the UI.
+/// </summary>
+public class ScreenDisplay
+{
+    public ScreenDisplay(System.Windows.Forms.Screen screen, int index)
+    {
+        DeviceName = screen.DeviceName;
+        DisplayName = ScreenUtilities.GetScreenLabel(screen, index);
+    }
+
+    public string DeviceName { get; }
+
+    public string DisplayName { get; }
+}

src/DesktopMagic/Helpers/ScreenUtilities.cs

@@ -0,0 +1,266 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.InteropServices;
+using System.Windows;
+
+namespace DesktopMagic.Helpers;
+
+/// <summary>
+/// Helpers for enumerating screens and converting between percentage based
+/// positions/sizes (relative to a screen's bounds) and absolute positions.
+/// All conversions work in WPF DIP space because WPF window <see cref="Window.Left"/>,
+/// <see cref="Window.Top"/>, <see cref="Window.Width"/> and <see cref="Window.Height"/>
+/// are expressed in device independent pixels, while <see cref="System.Windows.Forms.Screen.Bounds"/>
+/// is expressed in physical pixels. Each screen is therefore converted to DIP space
+/// using its own DPI scaling factor.
+/// </summary>
+public static class ScreenUtilities
+{
+    private const uint MonitorDefaultToNearest = 0x00000002;
+
+    private const int MDT_EFFECTIVE_DPI = 0;
+
+    /// <summary>
+    /// Gets the list of all screens currently connected, in the order reported by Windows.
+    /// </summary>
+    public static List<System.Windows.Forms.Screen> GetAllScreens()
+    {
+        return System.Windows.Forms.Screen.AllScreens.ToList();
+    }
+
+    /// <summary>
+    /// Gets the screen matching the given device name (e.g. "\\.\DISPLAY1"), or null.
+    /// </summary>
+    public static System.Windows.Forms.Screen? GetScreenByDeviceName(string? deviceName)
+    {
+        if (string.IsNullOrWhiteSpace(deviceName))
+        {
+            return null;
+        }
+
+        return System.Windows.Forms.Screen.AllScreens.FirstOrDefault(screen => string.Equals(screen.DeviceName, deviceName, StringComparison.OrdinalIgnoreCase));
+    }
+
+    /// <summary>
+    /// Gets the primary screen, or the first available screen as a fallback.
+    /// </summary>
+    public static System.Windows.Forms.Screen GetPrimaryScreen()
+    {
+        return System.Windows.Forms.Screen.PrimaryScreen ?? System.Windows.Forms.Screen.AllScreens.FirstOrDefault()
+            ?? throw new InvalidOperationException("No screens detected.");
+    }
+
+    /// <summary>
+    /// Aspect ratio (Width / Height) of the screen's bounds.
+    /// </summary>
+    public static double GetAspectRatio(System.Windows.Forms.Screen screen)
+    {
+        if (screen.Bounds.Height == 0)
+        {
+            return 0;
+        }
+
+        return screen.Bounds.Width / (double)screen.Bounds.Height;
+    }
+
+    /// <summary>
+    /// Converts a percentage based position (0..1 relative to the screen bounds) to an absolute
+    /// WPF position (DIPs) on that screen.
+    /// </summary>
+    public static Point PercentToPosition(Point percent, System.Drawing.Rectangle bounds)
+    {
+        Rect dips = GetScreenDips(bounds);
+        return new Point(
+            dips.Left + (percent.X * dips.Width),
+            dips.Top + (percent.Y * dips.Height));
+    }
+
+    /// <summary>
+    /// Converts an absolute WPF position (DIPs) to a percentage (0..1) of the screen bounds.
+    /// </summary>
+    public static Point PositionToPercent(Point position, System.Drawing.Rectangle bounds)
+    {
+        Rect dips = GetScreenDips(bounds);
+        if (dips.Width == 0 || dips.Height == 0)
+        {
+            return new Point(0.05, 0.05);
+        }
+
+        return new Point(
+            (position.X - dips.Left) / dips.Width,
+            (position.Y - dips.Top) / dips.Height);
+    }
+
+    /// <summary>
+    /// Converts a percentage based size (0..1 of the screen bounds) to an absolute WPF size (DIPs).
+    /// </summary>
+    public static Point PercentSizeToSize(Point percent, System.Drawing.Rectangle bounds)
+    {
+        Rect dips = GetScreenDips(bounds);
+        return new Point(
+            percent.X * dips.Width,
+            percent.Y * dips.Height);
+    }
+
+    /// <summary>
+    /// Converts an absolute WPF size (DIPs) to a percentage (0..1) of the screen bounds.
+    /// </summary>
+    public static Point SizeToPercent(Point size, System.Drawing.Rectangle bounds)
+    {
+        Rect dips = GetScreenDips(bounds);
+        if (dips.Width == 0 || dips.Height == 0)
+        {
+            return new Point(0.3, 0.3);
+        }
+
+        return new Point(
+            size.X / dips.Width,
+            size.Y / dips.Height);
+    }
+
+    /// <summary>
+    /// Clamps an absolute WPF position (DIPs) so that the window (of the given size)
+    /// stays within the screen bounds. This prevents widgets from being moved to another screen.
+    /// </summary>
+    public static Point ClampToScreenBounds(Point topLeft, Size size, System.Drawing.Rectangle bounds)
+    {
+        Rect dips = GetScreenDips(bounds);
+        double x = topLeft.X;
+        double y = topLeft.Y;
+
+        if (size.Width <= dips.Width)
+        {
+            x = Math.Clamp(x, dips.Left, dips.Right - size.Width);
+        }
+        else
+        {
+            x = dips.Left;
+        }
+
+        if (size.Height <= dips.Height)
+        {
+            y = Math.Clamp(y, dips.Top, dips.Bottom - size.Height);
+        }
+        else
+        {
+            y = dips.Top;
+        }
+
+        return new Point(x, y);
+    }
+
+    /// <summary>
+    /// Builds a human readable label for a screen, e.g. "Display 1 · DELL U2715H · 3840x2160".
+    /// </summary>
+    public static string GetScreenLabel(System.Windows.Forms.Screen screen, int index)
+    {
+        string name = GetFriendlyName(screen);
+        string resolution = $"{screen.Bounds.Width}x{screen.Bounds.Height}";
+
+        return string.IsNullOrWhiteSpace(name) || string.Equals(name, "Generic PnP Monitor", StringComparison.OrdinalIgnoreCase)
+            ? $"Display {index + 1} · {resolution}"
+            : $"Display {index + 1} · {name} · {resolution}";
+    }
+
+    /// <summary>
+    /// Gets the friendly monitor model name (e.g. "DELL U2715H") for the given screen,
+    /// or an empty string when it cannot be determined.
+    /// </summary>
+    public static string GetFriendlyName(System.Windows.Forms.Screen screen)
+    {
+        try
+        {
+            var device = new DISPLAY_DEVICE { cb = (uint)Marshal.SizeOf<DISPLAY_DEVICE>() };
+            if (EnumDisplayDevices(screen.DeviceName, 0, ref device, 0))
+            {
+                var monitor = new DISPLAY_DEVICE { cb = (uint)Marshal.SizeOf<DISPLAY_DEVICE>() };
+                if (EnumDisplayDevices(device.DeviceName, 0, ref monitor, 0))
+                {
+                    return monitor.DeviceString;
+                }
+            }
+        }
+        catch (Exception)
+        {
+            // Fall through to an empty name.
+        }
+
+        return string.Empty;
+    }
+
+    /// <summary>
+    /// Gets the screen bounds converted to WPF DIP space using the screen's own DPI scaling factor.
+    /// </summary>
+    private static Rect GetScreenDips(System.Drawing.Rectangle bounds)
+    {
+        double scale = GetDpiScale(bounds);
+        return new Rect(
+            bounds.Left / scale,
+            bounds.Top / scale,
+            bounds.Width / scale,
+            bounds.Height / scale);
+    }
+
+    /// <summary>
+    /// Gets the DPI scaling factor (relative to 96 DPI) of the screen containing the given bounds.
+    /// </summary>
+    private static double GetDpiScale(System.Drawing.Rectangle bounds)
+    {
+        try
+        {
+            var center = new POINT
+            {
+                X = bounds.Left + (bounds.Width / 2),
+                Y = bounds.Top + (bounds.Height / 2)
+            };
+            IntPtr monitor = MonitorFromPoint(center, MonitorDefaultToNearest);
+            if (GetDpiForMonitor(monitor, MDT_EFFECTIVE_DPI, out uint dpiX, out _) == 0)
+            {
+                return dpiX / 96.0;
+            }
+        }
+        catch (Exception)
+        {
+            // Fall through to no scaling if DPI APIs are unavailable.
+        }
+
+        return 1.0;
+    }
+
+    [DllImport("user32.dll")]
+    private static extern IntPtr MonitorFromPoint(POINT point, uint dwFlags);
+
+    [DllImport("shcore.dll")]
+    private static extern int GetDpiForMonitor(IntPtr hMonitor, int dpiType, out uint dpiX, out uint dpiY);
+
+    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
+    private static extern bool EnumDisplayDevices(string? lpDevice, uint iDevNum, ref DISPLAY_DEVICE lpDisplayDevice, uint dwFlags);
+
+    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
+    private struct DISPLAY_DEVICE
+    {
+        public uint cb;
+
+        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
+        public string DeviceName;
+
+        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
+        public string DeviceString;
+
+        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
+        public string DeviceID;
+
+        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
+        public string DeviceKey;
+
+        public uint StateFlags;
+    }
+
+    [StructLayout(LayoutKind.Sequential)]
+    private struct POINT
+    {
+        public int X;
+        public int Y;
+    }
+}

src/DesktopMagic/Manager.cs

@@ -5,6 +5,7 @@ using DesktopMagic.Settings;
 
 using System;
 using System.Collections.Generic;
+using System.Drawing;
 using System.IO;
 using System.Linq;
 using System.Text.Json;
@@ -35,6 +36,9 @@ public sealed class Manager
         }
     }
 
+    // Name of the built-in layout that shows no widgets on a screen.
+    public const string EmptyLayoutName = "Empty";
+
     // Plugin management
     private readonly Dictionary<uint, InternalPluginData> _plugins = [];
     private readonly Dictionary<PluginMetadata, Type> _builtInPlugins = new()
@@ -65,6 +69,13 @@ public sealed class Manager
     public DesktopMagicSettings Settings { get; set; } = new();
     public bool IsLoaded { get; set; } = false;
 
+    // Screen selection (which screen is currently edited in the UI)
+    public string? SelectedScreenDeviceName { get; set; }
+
+    public System.Windows.Forms.Screen SelectedScreen => ScreenUtilities.GetScreenByDeviceName(SelectedScreenDeviceName) ?? ScreenUtilities.GetPrimaryScreen();
+
+    public Layout SelectedLayout => GetLayoutForScreen(SelectedScreen);
+
     private readonly JsonSerializerOptions _jsonSettingsOptions = new()
     {
         Converters = { new ColorJsonConverter() }
@@ -137,20 +148,46 @@ public sealed class Manager
         App.Logger.LogInfo($"Loaded {_plugins.Count} plugins", source: "Manager");
     }
 
-    public void LoadPlugin(uint pluginId, Action<InternalPluginData>? onPluginLoaded = null)
+    /// <summary>
+    /// Loads (or unloads) the given plugin on every screen that currently uses the given layout.
+    /// This keeps screens sharing a layout in sync when plugins are enabled or disabled.
+    /// </summary>
+    public void LoadPlugin(uint pluginId, Layout layout, Action<InternalPluginData>? onPluginLoaded = null)
     {
         if (!_plugins.TryGetValue(pluginId, out InternalPluginData? internalPluginData))
         {
             return;
         }
 
-        if (!Settings.CurrentLayout.Plugins.TryGetValue(pluginId, out PluginSettings? pluginSettings))
+        if (!layout.Plugins.TryGetValue(pluginId, out PluginSettings? pluginSettings))
         {
             pluginSettings = new PluginSettings();
-            Settings.CurrentLayout.Plugins.Add(pluginId, pluginSettings);
+            layout.Plugins.Add(pluginId, pluginSettings);
         }
 
-        IPluginWindow? existingWindow = PluginWindows.FirstOrDefault(w => w.PluginMetadata.Id == internalPluginData.Metadata.Id);
+        pluginSettings.Metadata = internalPluginData.Metadata;
+        pluginSettings.Owner = layout;
+
+        foreach (System.Windows.Forms.Screen screen in ScreenUtilities.GetAllScreens())
+        {
+            if (GetLayoutForScreen(screen) == layout)
+            {
+                EnsurePluginWindow(screen, layout, internalPluginData, pluginSettings, onPluginLoaded);
+            }
+        }
+
+        layout.UpdatePlugins();
+    }
+
+    /// <summary>
+    /// Creates or closes the plugin window for a single screen, based on the plugin settings.
+    /// </summary>
+    private void EnsurePluginWindow(System.Windows.Forms.Screen screen, Layout layout, InternalPluginData internalPluginData, PluginSettings pluginSettings, Action<InternalPluginData>? onPluginLoaded)
+    {
+        string screenDeviceName = screen.DeviceName;
+        Rectangle screenBounds = screen.Bounds;
+
+        IPluginWindow? existingWindow = PluginWindows.FirstOrDefault(w => w.PluginMetadata.Id == internalPluginData.Metadata.Id && w.ScreenDeviceName == screenDeviceName);
 
         if (existingWindow is not null || !pluginSettings.Enabled)
         {
@@ -176,21 +213,21 @@ public sealed class Manager
 
         if (_builtInPlugins.TryGetValue(internalPluginData.Metadata, out Type? pluginType))
         {
-            window = new PluginWindow((Api.Plugin)Activator.CreateInstance(pluginType)!, internalPluginData.Metadata, pluginSettings)
+            window = new PluginWindow((Api.Plugin)Activator.CreateInstance(pluginType)!, internalPluginData.Metadata, pluginSettings, screenBounds, screenDeviceName)
             {
                 Title = internalPluginData.Metadata.Id.ToString()
             };
         }
         else if (internalPluginData.Type == PluginType.Web)
         {
-            window = new WebPluginWindow(internalPluginData.Metadata, pluginSettings, internalPluginData.DirectoryPath)
+            window = new WebPluginWindow(internalPluginData.Metadata, pluginSettings, internalPluginData.DirectoryPath, screenBounds, screenDeviceName)
             {
                 Title = internalPluginData.Metadata.Id.ToString()
             };
         }
         else
         {
-            window = new PluginWindow(internalPluginData.Metadata, pluginSettings, internalPluginData.DirectoryPath)
+            window = new PluginWindow(internalPluginData.Metadata, pluginSettings, internalPluginData.DirectoryPath, screenBounds, screenDeviceName)
             {
                 Title = internalPluginData.Metadata.Id.ToString()
             };
@@ -205,10 +242,21 @@ public sealed class Manager
 
         Action exitHandler = () =>
         {
-            PluginWindows.Remove(window);
+            // Close the widget on every screen using this layout
+            foreach (System.Windows.Forms.Screen sharedScreen in ScreenUtilities.GetAllScreens())
+            {
+                if (GetLayoutForScreen(sharedScreen) == layout)
+                {
+                    IPluginWindow? sharedWindow = PluginWindows.FirstOrDefault(w => w.PluginMetadata.Id == internalPluginData.Metadata.Id && w.ScreenDeviceName == sharedScreen.DeviceName);
+                    if (sharedWindow is not null)
+                    {
+                        PluginWindows.Remove(sharedWindow);
                         BlockWindowsClosing = false;
-            window.Close();
+                        sharedWindow.Close();
                         BlockWindowsClosing = true;
+                    }
+                }
+            }
             pluginSettings.Enabled = false;
         };
 
@@ -255,7 +303,9 @@ public sealed class Manager
         {
             Settings = new DesktopMagicSettings();
             Settings.Layouts.Add(new Layout("Default"));
+            Settings.Layouts.Add(new Layout(EmptyLayoutName));
             Settings.Themes.Add(new Theme("Default"));
+            Settings.SchemaVersion = 1;
             return;
         }
 
@@ -272,9 +322,62 @@ public sealed class Manager
             Settings.Themes.Add(new Theme("Default"));
         }
 
+        if (Settings.SchemaVersion < 1)
+        {
+            MigrateToScreenAwareSettings();
+            Settings.SchemaVersion = 1;
+        }
+
+        if (!Settings.Layouts.Any(layout => layout.Name == EmptyLayoutName))
+        {
+            Settings.Layouts.Add(new Layout(EmptyLayoutName));
+        }
+
         SettingsChanged?.Invoke();
     }
 
+    /// <summary>
+    /// Migrates legacy settings to screen-aware layouts:
+    /// records the primary screen aspect ratio on each layout and converts
+    /// absolute pixel positions/sizes to percentages of the primary screen bounds.
+    /// </summary>
+    private void MigrateToScreenAwareSettings()
+    {
+        App.Logger.LogInfo("Migrating settings to screen-aware layouts", source: "Manager");
+
+        System.Windows.Forms.Screen primaryScreen = ScreenUtilities.GetPrimaryScreen();
+        double aspectRatio = ScreenUtilities.GetAspectRatio(primaryScreen);
+        Rectangle bounds = primaryScreen.Bounds;
+
+        foreach (Layout layout in Settings.Layouts)
+        {
+            if (layout.ScreenAspectRatio <= 0)
+            {
+                layout.ScreenAspectRatio = aspectRatio;
+            }
+
+            foreach (PluginSettings plugin in layout.Plugins.Values)
+            {
+                if (plugin.Position.X > 1 || plugin.Position.Y > 1 || plugin.Position.X < 0 || plugin.Position.Y < 0)
+                {
+                    plugin.Position = ScreenUtilities.PositionToPercent(new System.Windows.Point(plugin.Position.X, plugin.Position.Y), bounds);
+                }
+
+                if (plugin.Size.X > 1 || plugin.Size.Y > 1)
+                {
+                    plugin.Size = ScreenUtilities.SizeToPercent(new System.Windows.Point(plugin.Size.X, plugin.Size.Y), bounds);
+                }
+            }
+        }
+
+        if (Settings.ScreenLayouts.Count == 0)
+        {
+            Settings.ScreenLayouts[primaryScreen.DeviceName] = Settings.CurrentLayoutName ?? "Default";
+        }
+
+        App.Logger.LogInfo("Settings migrated to screen-aware layouts", source: "Manager");
+    }
+
     public void SaveSettings()
     {
         if (!IsLoaded)
@@ -292,9 +395,60 @@ public sealed class Manager
 
     #region Layout Management
 
+    /// <summary>
+    /// Resolves the layout that should be applied to the given screen:
+    /// 1. the layout explicitly bound to this screen's device name,
+    /// 2. the layout with the closest matching aspect ratio,
+    /// 3. the first layout.
+    /// </summary>
+    public Layout GetLayoutForScreen(System.Windows.Forms.Screen screen)
+    {
+        if (Settings.ScreenLayouts.TryGetValue(screen.DeviceName, out string? layoutName))
+        {
+            Layout? bound = Settings.Layouts.FirstOrDefault(layout => layout.Name == layoutName);
+            if (bound is not null)
+            {
+                return bound;
+            }
+        }
+
+        double targetRatio = ScreenUtilities.GetAspectRatio(screen);
+        Layout? byAspectRatio = Settings.Layouts
+            .Where(layout => layout.ScreenAspectRatio > 0)
+            .OrderBy(layout => Math.Abs(layout.ScreenAspectRatio - targetRatio))
+            .FirstOrDefault();
+
+        if (byAspectRatio is not null)
+        {
+            return byAspectRatio;
+        }
+
+        return Settings.Layouts.FirstOrDefault() ?? new Layout("ERROR");
+    }
+
+    /// <summary>
+    /// Binds the given layout to the given screen on this machine.
+    /// </summary>
+    public void BindLayoutToScreen(System.Windows.Forms.Screen screen, Layout layout)
+    {
+        Settings.ScreenLayouts[screen.DeviceName] = layout.Name;
+        SaveSettings();
+    }
+
+    /// <summary>
+    /// Gets all plugin windows currently shown on the given screen.
+    /// </summary>
+    public IEnumerable<IPluginWindow> GetWindowsForScreen(string screenDeviceName)
+    {
+        return PluginWindows.Where(window => window.ScreenDeviceName == screenDeviceName).ToList();
+    }
+
+    /// <summary>
+    /// Loads all screens' layouts at once, opening the enabled widgets of every screen.
+    /// </summary>
     public void LoadLayout(Action? onComplete = null)
     {
-        App.Logger.LogInfo("Loading layout", source: "Manager");
+        App.Logger.LogInfo("Loading layouts", source: "Manager");
         BlockWindowsClosing = false;
 
         foreach (IPluginWindow window in PluginWindows)
@@ -305,37 +459,77 @@ public sealed class Manager
         BlockWindowsClosing = true;
         PluginWindows.Clear();
 
+        foreach (System.Windows.Forms.Screen screen in ScreenUtilities.GetAllScreens())
+        {
+            Layout layout = GetLayoutForScreen(screen);
+            LoadScreen(screen, layout);
+        }
+
+        onComplete?.Invoke();
+        App.Logger.LogInfo("Layouts loaded", source: "Manager");
+    }
+
+    /// <summary>
+    /// Reloads the widgets of a single screen using the layout currently bound to it.
+    /// </summary>
+    public void ReloadScreen(System.Windows.Forms.Screen screen)
+    {
+        App.Logger.LogInfo($"Reloading screen {screen.DeviceName}", source: "Manager");
+
+        List<IPluginWindow> windows = PluginWindows.Where(window => window.ScreenDeviceName == screen.DeviceName).ToList();
+
+        BlockWindowsClosing = false;
+        foreach (IPluginWindow window in windows)
+        {
+            window.Close();
+        }
+
+        BlockWindowsClosing = true;
+        PluginWindows.RemoveAll(window => windows.Contains(window));
+
+        Layout layout = GetLayoutForScreen(screen);
+        LoadScreen(screen, layout);
+    }
+
+    private void LoadScreen(System.Windows.Forms.Screen screen, Layout layout)
+    {
+        App.Logger.LogInfo($"Loading layout \"{layout.Name}\" for screen {screen.DeviceName}", source: "Manager");
+
+        // The empty layout intentionally shows no widgets and is never populated.
+        if (layout.Name == EmptyLayoutName)
+        {
+            return;
+        }
+
         // Load plugins
         foreach (uint pluginId in _plugins.Keys)
         {
             InternalPluginData internalPluginData = _plugins[pluginId];
 
             // Add plugin to layout if it doesn't exist
-            if (!Settings.CurrentLayout.Plugins.TryGetValue(pluginId, out PluginSettings? pluginSettings))
+            if (!layout.Plugins.TryGetValue(pluginId, out PluginSettings? pluginSettings))
             {
-                Settings.CurrentLayout.Plugins.Add(pluginId, new PluginSettings() { Metadata = internalPluginData.Metadata });
+                layout.Plugins.Add(pluginId, new PluginSettings() { Metadata = internalPluginData.Metadata, Owner = layout });
                 continue;
             }
 
             pluginSettings.Metadata = internalPluginData.Metadata;
+            pluginSettings.Owner = layout;
 
             if (pluginSettings.Enabled)
             {
-                LoadPlugin(pluginId);
+                EnsurePluginWindow(screen, layout, internalPluginData, pluginSettings, null);
             }
         }
 
         // Remove plugins that are not loaded anymore
-        List<uint> pluginIdsToRemove = Settings.CurrentLayout.Plugins.Keys.Where(id => !_plugins.ContainsKey(id)).ToList();
+        List<uint> pluginIdsToRemove = layout.Plugins.Keys.Where(id => !_plugins.ContainsKey(id)).ToList();
         foreach (uint pluginId in pluginIdsToRemove)
         {
-            Settings.CurrentLayout.Plugins.Remove(pluginId);
+            layout.Plugins.Remove(pluginId);
         }
 
-        Settings.CurrentLayout.UpdatePlugins();
-
-        onComplete?.Invoke();
-        App.Logger.LogInfo("Layout loaded", source: "Manager");
+        layout.UpdatePlugins();
     }
 
     #endregion

src/DesktopMagic/Pages/MainPage.xaml

@@ -32,7 +32,7 @@
         </ui:Card>
 
         <ScrollViewer Background="#FFBBBBBB" PreviewMouseWheel="ScrollViewer_PreviewMouseWheel" Grid.Row="1" VerticalAlignment="Stretch" VerticalContentAlignment="Top">
-            <ItemsControl x:Name="pluginsItemsControl" ItemsSource="{Binding Settings.CurrentLayout.Plugins}">
+            <ItemsControl x:Name="pluginsItemsControl" ItemsSource="{Binding SelectedLayout.Plugins}">
                 <ItemsControl.ItemTemplate>
                     <DataTemplate>
                         <ui:CardExpander Tag="{Binding}" Margin="0 0 0 5" Expanded="OptionsCardExpander_Expanded">
@@ -70,17 +70,24 @@
 
         <ui:Card Grid.Row="2" Grid.ColumnSpan="2" Margin="0 5 0 0" Padding="5">
             <Grid>
+                <Grid.RowDefinitions>
+                    <RowDefinition Height="auto" />
+                    <RowDefinition Height="5" />
+                    <RowDefinition Height="auto" />
+                </Grid.RowDefinitions>
                 <Grid.ColumnDefinitions>
                     <ColumnDefinition Width="1*" />
                     <ColumnDefinition Width="5" />
-                    <ColumnDefinition Width="0.5*" />
-                    <ColumnDefinition Width="5" />
-                    <ColumnDefinition Width="0.5*" />
+                    <ColumnDefinition Width="1*" />
                 </Grid.ColumnDefinitions>
 
-                <ComboBox x:Name="layoutsComboBox" ItemsSource="{Binding Settings.Layouts}" DisplayMemberPath="Name" SelectedValue="{Binding Settings.CurrentLayoutName}" SelectedValuePath="Name" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Padding="4" SelectionChanged="LayoutsComboBox_SelectionChanged" />
-                <ui:Button x:Name="newLayoutButton" Content="{DynamicResource newLayout}" Grid.Column="2" Icon="{ui:SymbolIcon Add24}"  HorizontalAlignment="Stretch" Click="NewLayoutButton_Click" FontWeight="Regular"/>
-                <ui:Button x:Name="removeLayoutButton" Content="{DynamicResource deleteLayout}" Icon="{ui:SymbolIcon Delete24}"  Grid.Column="4" HorizontalAlignment="Stretch" Click="RemoveLayoutButton_Click" FontWeight="Regular"/>
+                <ComboBox x:Name="screensComboBox" ItemsSource="{Binding Screens}" DisplayMemberPath="DisplayName" SelectedValue="{Binding SelectedScreenId}" SelectedValuePath="DeviceName" VerticalAlignment="Center" />
+                <ComboBox x:Name="layoutsComboBox" Grid.Column="2" ItemsSource="{Binding Settings.Layouts}" DisplayMemberPath="Name" SelectedValue="{Binding SelectedLayoutName}" SelectedValuePath="Name" VerticalAlignment="Center" SelectionChanged="LayoutsComboBox_SelectionChanged" />
+
+                <StackPanel Grid.Row="2" Grid.ColumnSpan="3" Orientation="Horizontal" HorizontalAlignment="Right">
+                    <ui:Button x:Name="newLayoutButton" Content="{DynamicResource newLayout}" Icon="{ui:SymbolIcon Add24}" Margin="0,0,5,0" Click="NewLayoutButton_Click" FontWeight="Regular" />
+                    <ui:Button x:Name="removeLayoutButton" Content="{DynamicResource deleteLayout}" Icon="{ui:SymbolIcon Delete24}" Margin="0,0,5,0" Click="RemoveLayoutButton_Click" FontWeight="Regular" />
+                </StackPanel>
             </Grid>
         </ui:Card>
     </Grid>

src/DesktopMagic/Pages/MainPage.xaml.cs

@@ -20,7 +20,6 @@ public partial class MainPage : Page
 {
     private readonly Manager _manager = Manager.Instance;
     private readonly MainWindowDataContext _dataContext;
-    private bool _isLoadingLayout = false;
 
     public MainPage()
     {
@@ -45,6 +44,8 @@ public partial class MainPage : Page
     {
         // Initialize edit checkbox state
         editCheckBox.IsChecked = _manager.IsEditMode;
+
+        _dataContext.RefreshScreens();
     }
 
     private void MainPage_Unloaded(object sender, RoutedEventArgs e)
@@ -85,7 +86,7 @@ public partial class MainPage : Page
 
         uint pluginId = uint.Parse(checkBox.Tag.ToString()!);
 
-        _manager.LoadPlugin(pluginId, (internalPluginData) =>
+        _manager.LoadPlugin(pluginId, _manager.SelectedLayout, (internalPluginData) =>
         {
             Dispatcher.Invoke(() =>
             {
@@ -145,32 +146,46 @@ public partial class MainPage : Page
 
     private void LayoutsComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
     {
-        // Prevent recursive calls and only process if fully loaded
-        if (_isLoadingLayout || !_manager.IsLoaded || !IsLoaded)
+        ApplySelectedLayout();
+    }
+
+    /// <summary>
+    /// Binds the currently selected layout to the currently selected screen and reloads it.
+    /// No-op when the layout is already the one bound to the screen (e.g. programmatic resets).
+    /// </summary>
+    private void ApplySelectedLayout()
+    {
+        if (_dataContext.SelectedScreenId is null)
         {
             return;
         }
 
-        // Check if this is actually a user-initiated change
-        // by verifying that the removed and added items are different
-        if (e.RemovedItems.Count > 0 && e.AddedItems.Count > 0)
-        {
-            if (e.RemovedItems[0] == e.AddedItems[0])
+        System.Windows.Forms.Screen? screen = ScreenUtilities.GetScreenByDeviceName(_dataContext.SelectedScreenId);
+        if (screen is null)
         {
             return;
         }
+
+        string? layoutName = _dataContext.SelectedLayoutName;
+        if (layoutName is null)
+        {
+            return;
         }
 
-        try
+        Layout? layout = _manager.Settings.Layouts.FirstOrDefault(l => l.Name == layoutName);
+        if (layout is null)
         {
-            _isLoadingLayout = true;
-            _manager.SaveSettings();
-            _manager.LoadLayout();
+            return;
         }
-        finally
+
+        if (_manager.GetLayoutForScreen(screen) == layout)
         {
-            _isLoadingLayout = false;
+            return;
         }
+
+        _manager.BindLayoutToScreen(screen, layout);
+        _manager.ReloadScreen(screen);
+        _dataContext.RefreshSelection();
     }
 
     private async void NewLayoutButton_Click(object sender, RoutedEventArgs e)
@@ -194,18 +209,11 @@ public partial class MainPage : Page
                 return;
             }
 
-            try
-            {
-                _isLoadingLayout = true;
             _manager.Settings.Layouts.Add(new Layout(inputDialog.ResponseText.Trim()));
-                _manager.Settings.CurrentLayoutName = inputDialog.ResponseText.Trim();
             _manager.SaveSettings();
-                _manager.LoadLayout();
-            }
-            finally
-            {
-                _isLoadingLayout = false;
-            }
+
+            // Select the new layout so the user can apply it to the current screen
+            _dataContext.SelectedLayoutName = inputDialog.ResponseText.Trim();
         }
     }
 
@@ -237,17 +245,40 @@ public partial class MainPage : Page
             return;
         }
 
-        try
+        Layout? layout = _manager.Settings.Layouts.FirstOrDefault(l => l.Name == _dataContext.SelectedLayoutName);
+        if (layout is null)
         {
-            _isLoadingLayout = true;
-            _ = _manager.Settings.Layouts.Remove(_manager.Settings.CurrentLayout);
+            return;
+        }
+
+        if (layout.Name == Manager.EmptyLayoutName)
+        {
+            Wpf.Ui.Controls.MessageBox cannotDeleteMessageBox = new Wpf.Ui.Controls.MessageBox
+            {
+                Title = App.AppName,
+                Content = (string)FindResource("cannotDeleteEmptyLayout"),
+                CloseButtonText = "Ok"
+            };
+            _ = await cannotDeleteMessageBox.ShowDialogAsync();
+            return;
+        }
+
+        _ = _manager.Settings.Layouts.Remove(layout);
+
+        // Remove any screen bindings pointing to the deleted layout
+        List<string> boundScreens = _manager.Settings.ScreenLayouts
+            .Where(kvp => kvp.Value == layout.Name)
+            .Select(kvp => kvp.Key)
+            .ToList();
+
+        foreach (string screenId in boundScreens)
+        {
+            _ = _manager.Settings.ScreenLayouts.Remove(screenId);
+        }
+
         _manager.SaveSettings();
         _manager.LoadLayout();
-        }
-        finally
-        {
-            _isLoadingLayout = false;
-        }
+        _dataContext.RefreshSelection();
     }
 
     #endregion

src/DesktopMagic/Pages/ThemePage.xaml

@@ -15,7 +15,7 @@
             <RowDefinition Height="auto" />
         </Grid.RowDefinitions>
         
-        <ui:ListView x:Name="themesListBox" Grid.Row="0" Grid.ColumnSpan="1" ItemsSource="{Binding Settings.Themes}" SelectedValue="{Binding Settings.CurrentLayout.CurrentThemeName}" SelectedValuePath="Name" SelectedIndex="2" SelectionMode="Single">
+        <ui:ListView x:Name="themesListBox" Grid.Row="0" Grid.ColumnSpan="1" ItemsSource="{Binding Settings.Themes}" SelectedValue="{Binding SelectedLayout.CurrentThemeName}" SelectedValuePath="Name" SelectedIndex="2" SelectionMode="Single">
             <ui:ListView.ItemTemplate>
                 <DataTemplate>
                     <Grid>

src/DesktopMagic/Pages/ThemePage.xaml.cs

@@ -69,7 +69,7 @@ public partial class ThemePage : Page
             }
 
             _manager.Settings.Themes.Add(new Theme(inputDialog.ResponseText.Trim()));
-            _manager.Settings.CurrentLayout.CurrentThemeName = inputDialog.ResponseText.Trim();
+            _manager.SelectedLayout.CurrentThemeName = inputDialog.ResponseText.Trim();
             _manager.SaveSettings();
         }
     }

src/DesktopMagic/Plugins/IPluginWindow.cs

@@ -13,6 +13,7 @@ public interface IPluginWindow
     PluginMetadata PluginMetadata { get; }
     string PluginFolderPath { get; }
     string Title { get; set; }
+    string ScreenDeviceName { get; }
 
     void Exit();
     void SetEditMode(bool enabled);

src/DesktopMagic/Plugins/PluginWindow.xaml.cs

@@ -39,6 +39,10 @@ public partial class PluginWindow : Window, IPluginWindow
     private Plugin? pluginClassInstance;
     private AssemblyLoadContext assemblyLoadContext;
 
+    private readonly Rectangle screenBounds;
+    private readonly string screenDeviceName;
+    private bool isUpdatingPosition = false;
+
     private CancellationTokenSource? pluginCancellationTokenSource;
     private FileSystemWatcher? pluginFileWatcher;
     private System.Timers.Timer? reloadDebounceTimer;
@@ -50,8 +54,9 @@ public partial class PluginWindow : Window, IPluginWindow
     public bool IsRunning { get; private set; } = true;
     public PluginMetadata PluginMetadata { get; private set; }
     public string PluginFolderPath { get; private set; }
+    public string ScreenDeviceName => screenDeviceName;
 
-    public PluginWindow(PluginMetadata pluginMetadata, PluginSettings settings, string pluginFolderPath)
+    public PluginWindow(PluginMetadata pluginMetadata, PluginSettings settings, string pluginFolderPath, Rectangle screenBounds, string screenDeviceName)
     {
         InitializeComponent();
 
@@ -81,6 +86,14 @@ public partial class PluginWindow : Window, IPluginWindow
                 };
                 ThemeChanged();
             }
+            else if (s.PropertyName == nameof(PluginSettings.Position))
+            {
+                UpdatePosition();
+            }
+            else if (s.PropertyName == nameof(PluginSettings.Size))
+            {
+                UpdateSize();
+            }
         };
 
         settings.Theme.PropertyChanged += (se, ev) =>
@@ -90,11 +103,15 @@ public partial class PluginWindow : Window, IPluginWindow
 
         PluginMetadata = pluginMetadata;
         this.settings = settings;
+        this.screenBounds = screenBounds;
+        this.screenDeviceName = screenDeviceName;
 
-        Left = settings.Position.X;
-        Top = settings.Position.Y;
-        Width = settings.Size.X;
-        Height = settings.Size.Y;
+        System.Windows.Point position = ScreenUtilities.PercentToPosition(settings.Position, screenBounds);
+        System.Windows.Point size = ScreenUtilities.PercentSizeToSize(settings.Size, screenBounds);
+        Left = position.X;
+        Top = position.Y;
+        Width = size.X;
+        Height = size.Y;
 
         PluginFolderPath = pluginFolderPath;
 
@@ -107,7 +124,7 @@ public partial class PluginWindow : Window, IPluginWindow
         }
     }
 
-    public PluginWindow(Plugin pluginClassInstance, PluginMetadata pluginMetadata, PluginSettings settings) : this(pluginMetadata, settings, string.Empty)
+    public PluginWindow(Plugin pluginClassInstance, PluginMetadata pluginMetadata, PluginSettings settings, Rectangle screenBounds, string screenDeviceName) : this(pluginMetadata, settings, string.Empty, screenBounds, screenDeviceName)
     {
         this.pluginClassInstance = pluginClassInstance;
     }
@@ -993,16 +1010,73 @@ public partial class PluginWindow : Window, IPluginWindow
         _ = StopPlugin(unloadAssembly: true);
     }
 
+    private void UpdatePosition()
+    {
+        if (isUpdatingPosition)
+        {
+            return;
+        }
+
+        System.Windows.Point position = ScreenUtilities.PercentToPosition(settings.Position, screenBounds);
+        if (position == new System.Windows.Point(Left, Top))
+        {
+            return;
+        }
+
+        isUpdatingPosition = true;
+        Left = position.X;
+        Top = position.Y;
+        isUpdatingPosition = false;
+    }
+
+    private void UpdateSize()
+    {
+        if (isUpdatingPosition)
+        {
+            return;
+        }
+
+        System.Windows.Point size = ScreenUtilities.PercentSizeToSize(settings.Size, screenBounds);
+        if (size == new System.Windows.Point(Width, Height))
+        {
+            return;
+        }
+
+        isUpdatingPosition = true;
+        Width = size.X;
+        Height = size.Y;
+        isUpdatingPosition = false;
+    }
+
     #region Window Events
 
     private void Window_LocationChanged(object sender, EventArgs e)
     {
-        settings.Position = new System.Windows.Point(Left, Top);
+        if (isUpdatingPosition)
+        {
+            return;
+        }
+
+        System.Windows.Point topLeft = new(Left, Top);
+        System.Windows.Point clamped = ScreenUtilities.ClampToScreenBounds(topLeft, new System.Windows.Size(ActualWidth, ActualHeight), screenBounds);
+
+        if (clamped != topLeft)
+        {
+            isUpdatingPosition = true;
+            Left = clamped.X;
+            Top = clamped.Y;
+            isUpdatingPosition = false;
+        }
+
+        settings.Position = ScreenUtilities.PositionToPercent(new System.Windows.Point(Left, Top), screenBounds);
     }
 
     private void Window_SizeChanged(object sender, SizeChangedEventArgs e)
     {
-        settings.Size = new System.Windows.Point(Width, Height);
+        if (!isUpdatingPosition)
+        {
+            settings.Size = ScreenUtilities.SizeToPercent(new System.Windows.Point(Width, Height), screenBounds);
+        }
 
         tileBar.CaptionHeight = ActualHeight - 10;
     }

src/DesktopMagic/Plugins/WebPluginWindow.xaml.cs

@@ -29,11 +29,16 @@ public partial class WebPluginWindow : Window, IPluginWindow
     private System.Timers.Timer? reloadDebounceTimer;
     private bool isReloading = false;
 
+    private readonly System.Drawing.Rectangle screenBounds;
+    private readonly string screenDeviceName;
+    private bool isUpdatingPosition = false;
+
     public bool IsRunning { get; private set; } = true;
     public PluginMetadata PluginMetadata { get; private set; }
     public string PluginFolderPath { get; private set; }
+    public string ScreenDeviceName => screenDeviceName;
 
-    public WebPluginWindow(PluginMetadata pluginMetadata, PluginSettings settings, string pluginFolderPath)
+    public WebPluginWindow(PluginMetadata pluginMetadata, PluginSettings settings, string pluginFolderPath, System.Drawing.Rectangle screenBounds, string screenDeviceName)
     {
         InitializeComponent();
 
@@ -63,6 +68,14 @@ public partial class WebPluginWindow : Window, IPluginWindow
                 };
                 ThemeChanged();
             }
+            else if (s.PropertyName == nameof(PluginSettings.Position))
+            {
+                UpdatePosition();
+            }
+            else if (s.PropertyName == nameof(PluginSettings.Size))
+            {
+                UpdateSize();
+            }
         };
 
         settings.Theme.PropertyChanged += (se, ev) =>
@@ -72,11 +85,15 @@ public partial class WebPluginWindow : Window, IPluginWindow
 
         PluginMetadata = pluginMetadata;
         this.settings = settings;
+        this.screenBounds = screenBounds;
+        this.screenDeviceName = screenDeviceName;
 
-        Left = settings.Position.X;
-        Top = settings.Position.Y;
-        Width = settings.Size.X;
-        Height = settings.Size.Y;
+        Point position = ScreenUtilities.PercentToPosition(settings.Position, screenBounds);
+        Point size = ScreenUtilities.PercentSizeToSize(settings.Size, screenBounds);
+        Left = position.X;
+        Top = position.Y;
+        Width = size.X;
+        Height = size.Y;
 
         PluginFolderPath = pluginFolderPath;
 
@@ -263,14 +280,71 @@ public partial class WebPluginWindow : Window, IPluginWindow
         }
     }
 
+    private void UpdatePosition()
+    {
+        if (isUpdatingPosition)
+        {
+            return;
+        }
+
+        Point position = ScreenUtilities.PercentToPosition(settings.Position, screenBounds);
+        if (position == new Point(Left, Top))
+        {
+            return;
+        }
+
+        isUpdatingPosition = true;
+        Left = position.X;
+        Top = position.Y;
+        isUpdatingPosition = false;
+    }
+
+    private void UpdateSize()
+    {
+        if (isUpdatingPosition)
+        {
+            return;
+        }
+
+        Point size = ScreenUtilities.PercentSizeToSize(settings.Size, screenBounds);
+        if (size == new Point(Width, Height))
+        {
+            return;
+        }
+
+        isUpdatingPosition = true;
+        Width = size.X;
+        Height = size.Y;
+        isUpdatingPosition = false;
+    }
+
     private void Window_LocationChanged(object sender, EventArgs e)
     {
-        settings.Position = new System.Windows.Point(Left, Top);
+        if (isUpdatingPosition)
+        {
+            return;
+        }
+
+        Point topLeft = new(Left, Top);
+        Point clamped = ScreenUtilities.ClampToScreenBounds(topLeft, new Size(ActualWidth, ActualHeight), screenBounds);
+
+        if (clamped != topLeft)
+        {
+            isUpdatingPosition = true;
+            Left = clamped.X;
+            Top = clamped.Y;
+            isUpdatingPosition = false;
+        }
+
+        settings.Position = ScreenUtilities.PositionToPercent(new Point(Left, Top), screenBounds);
     }
 
     private void Window_SizeChanged(object sender, SizeChangedEventArgs e)
     {
-        settings.Size = new System.Windows.Point(Width, Height);
+        if (!isUpdatingPosition)
+        {
+            settings.Size = ScreenUtilities.SizeToPercent(new Point(Width, Height), screenBounds);
+        }
 
         tileBar.CaptionHeight = ActualHeight - 10;
     }

src/DesktopMagic/Resources/Strings/StringResources.de.xaml

@@ -55,6 +55,7 @@
     <system:String x:Key="confirmDeleteTheme">Möchten Sie dieses Theme wirklich löschen?</system:String>
     <system:String x:Key="enterLayoutName">Layoutnamen eingeben:</system:String>
     <system:String x:Key="layoutAlreadyExists">Layout existiert bereits!</system:String>
+    <system:String x:Key="cannotDeleteEmptyLayout">Das leere Layout kann nicht gelöscht werden!</system:String>
     <system:String x:Key="enterThemeName">Themenamen eingeben:</system:String>
     <system:String x:Key="themeAlreadyExists">Theme existiert bereits!</system:String>
     <system:String x:Key="install">Installieren</system:String>

src/DesktopMagic/Resources/Strings/StringResources.en.xaml

@@ -56,6 +56,7 @@
     <system:String x:Key="enterLayoutName">Enter layout name</system:String>
     <system:String x:Key="layoutAlreadyExists">Layout already exists!</system:String>
     <system:String x:Key="cannotDeleteLastLayout">Can't delete last layout!</system:String>
+    <system:String x:Key="cannotDeleteEmptyLayout">Can't delete the empty layout!</system:String>
     <system:String x:Key="enterThemeName">Enter theme name</system:String>
     <system:String x:Key="themeAlreadyExists">Theme already exists!</system:String>
     <system:String x:Key="cannotDeleteLastTheme">Can't delete last theme!</system:String>

src/DesktopMagic/Settings/DesktopMagicSettings.cs

@@ -1,5 +1,6 @@
 using DesktopMagic.Plugins;
 
+using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.ComponentModel;
 using System.Linq;
@@ -22,7 +23,13 @@ public class DesktopMagicSettings : INotifyPropertyChanged
         init
         {
             themes = value;
-            themes.CollectionChanged += (s, e) => CurrentLayout.UpdateTheme();
+            themes.CollectionChanged += (s, e) =>
+            {
+                foreach (Layout layout in layouts)
+                {
+                    layout.UpdateTheme();
+                }
+            };
             OnPropertyChanged();
         }
     }
@@ -62,6 +69,18 @@ public class DesktopMagicSettings : INotifyPropertyChanged
         }
     }
 
+    /// <summary>
+    /// Maps screen device names (e.g. "\\.\DISPLAY1") to the layout applied on that screen.
+    /// The layouts themselves are portable and store their target aspect ratio.
+    /// </summary>
+    public Dictionary<string, string> ScreenLayouts { get; set; } = [];
+
+    /// <summary>
+    /// Version of the settings schema, used to migrate older settings files.
+    /// 0 = legacy (layouts not screen aware, pixel based positions).
+    /// </summary>
+    public int SchemaVersion { get; set; }
+
     public string? ModIoAccessToken { get; set; }
 
     public string? ReleaseInfoLastAppVersion { get; set; }
@@ -70,7 +89,13 @@ public class DesktopMagicSettings : INotifyPropertyChanged
 
     public DesktopMagicSettings()
     {
-        themes.CollectionChanged += (s, e) => CurrentLayout.UpdateTheme();
+        themes.CollectionChanged += (s, e) =>
+        {
+            foreach (Layout layout in layouts)
+            {
+                layout.UpdateTheme();
+            }
+        };
 
         layouts.CollectionChanged += (s, e) => OnPropertyChanged(nameof(CurrentLayout));
         layouts.CollectionChanged += (s, e) => OnPropertyChanged(nameof(CurrentLayoutName));

src/DesktopMagic/Settings/Layout.cs

@@ -16,6 +16,7 @@ public class Layout(string name) : INotifyPropertyChanged
     private string name = name;
     private string? currentThemeName = null;
     private Dictionary<uint, PluginSettings> plugins = [];
+    private double screenAspectRatio = 0;
 
     [JsonIgnore]
     public Theme Theme
@@ -60,6 +61,23 @@ public class Layout(string name) : INotifyPropertyChanged
         }
     }
 
+    /// <summary>
+    /// Aspect ratio (Width / Height) of the screen this layout was designed for.
+    /// Used to match layouts to screens and to make layouts portable across screens.
+    /// </summary>
+    public double ScreenAspectRatio
+    {
+        get => screenAspectRatio;
+        set
+        {
+            if (screenAspectRatio != value)
+            {
+                screenAspectRatio = value;
+                OnPropertyChanged();
+            }
+        }
+    }
+
     public void UpdatePlugins()
     {
         plugins = plugins.ToDictionary();

src/DesktopMagic/Settings/PluginSettings.cs

@@ -19,20 +19,24 @@ public class PluginSettings : INotifyPropertyChanged
     private List<SettingElement> settings = [];
     private Dictionary<string, JsonElement> state = [];
     private bool enabled = false;
-    private Point position = new Point(100, 100);
-    private Point size = new Point(300, 300);
+    private Point position = new Point(0.05, 0.05);
+    private Point size = new Point(0.3, 0.3);
 
     // Only for internal use to show the name of the plugin in the main window
     [JsonIgnore]
     public PluginMetadata Metadata { get; set; } = new();
 
+    // The layout this plugin belongs to, used to resolve the fallback theme
+    [JsonIgnore]
+    public Layout? Owner { get; set; }
+
     [JsonIgnore]
     public Theme Theme
     {
         get
         {
             DesktopMagicSettings settings = MainWindowDataContext.GetSettings();
-            return settings.Themes.FirstOrDefault(t => t.Name == currentThemeName) ?? settings.CurrentLayout.Theme;
+            return settings.Themes.FirstOrDefault(t => t.Name == currentThemeName) ?? Owner?.Theme ?? settings.CurrentLayout.Theme;
         }
     }
 
@@ -93,6 +97,9 @@ public class PluginSettings : INotifyPropertyChanged
         }
     }
 
+    /// <summary>
+    /// Position of the plugin window as percentages (0..1) of the owning screen's bounds.
+    /// </summary>
     public Point Position
     {
         get => position;
@@ -106,6 +113,9 @@ public class PluginSettings : INotifyPropertyChanged
         }
     }
 
+    /// <summary>
+    /// Size of the plugin window as percentages (0..1) of the owning screen's bounds.
+    /// </summary>
     public Point Size
     {
         get => size;