From 993c34642afbd877fc5addafc93688859742d6fb Mon Sep 17 00:00:00 2001
From: Raul Avila Catala <cl2raul66@hotmail.com>
Date: Sun, 30 Aug 2026 00:44:07 -0600
Subject: [PATCH] =?UTF-8?q?feat:=20IDefaultUiValues=20=E2=80=94=20sistema?=
 =?UTF-8?q?=20centralizado=20de=20defaults=20de=20UI=20(#36)?=
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Content-Type: text/plain; charset=UTF-8
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Implementa contrato IDefaultUiValues en Core (internal) con
WindowUiDefaults, ControlUiDefaults y FontSpec como records.
CoreUiDefaults lee colores via GetSysColor y aporta diccionario
IReadOnlyDictionary<Type,ControlUiDefaults>. Win32UiDefaults
expone defaults tematicos (IButton 30px, ILabel 23px) y
FontSpec.SystemTheme.

Fix bug visual: ControlProcedures.GetDefaultFont ahora usa
NONCLIENTMETRICS.lfMessageFont cacheado con DeleteObject y
fallback CreateFontFromSpec DPI-aware, corrige leak de HFONT.
ControlBase.MeasureText* reemplaza GetStockObject(17) por
fallback tematico y soporte pre-HWND. Button.MeasureContent
usa PreferredHeight del provider con escalado DPI.

Provider registrado primero en Application.Initialize y
MasterRouter maneja WM_SETTINGCHANGE/WM_DPICHANGED con
InvalidateDefaultFont + broadcast WM_SETFONT.

Closes #36
---
 .../Core/Application.cs                       |  3 +
 src/EasyWindowsApplication/Core/Constants.cs  |  8 ++
 .../Core/ControlBase.cs                       | 18 +++--
 .../Core/HandleRegistry.cs                    |  6 ++
 .../Core/MasterRouter.cs                      | 30 +++++++
 .../Core/UiDefaults/ControlUiDefaults.cs      | 10 +++
 .../Core/UiDefaults/CoreUiDefaults.cs         | 52 ++++++++++++
 .../UiDefaults/DefaultUiValuesExtensions.cs   | 10 +++
 .../Core/UiDefaults/FontSpec.cs               | 15 ++++
 .../Core/UiDefaults/IDefaultUiValues.cs       | 18 +++++
 .../Core/UiDefaults/UiDefaultsProvider.cs     | 16 ++++
 .../Core/UiDefaults/WindowUiDefaults.cs       | 13 +++
 .../Win32ControlsModule/Backend/Controls.cs   | 23 ++++++
 .../Win32ControlsModule/Backend/Procedures.cs | 72 ++++++++++++++++-
 .../Win32ControlsModule/Backend/Win32.cs      | 81 +++++++++++++++++++
 .../Backend/Win32UiDefaults.cs                | 19 +++++
 16 files changed, 386 insertions(+), 8 deletions(-)
 create mode 100644 src/EasyWindowsApplication/Core/UiDefaults/ControlUiDefaults.cs
 create mode 100644 src/EasyWindowsApplication/Core/UiDefaults/CoreUiDefaults.cs
 create mode 100644 src/EasyWindowsApplication/Core/UiDefaults/DefaultUiValuesExtensions.cs
 create mode 100644 src/EasyWindowsApplication/Core/UiDefaults/FontSpec.cs
 create mode 100644 src/EasyWindowsApplication/Core/UiDefaults/IDefaultUiValues.cs
 create mode 100644 src/EasyWindowsApplication/Core/UiDefaults/UiDefaultsProvider.cs
 create mode 100644 src/EasyWindowsApplication/Core/UiDefaults/WindowUiDefaults.cs
 create mode 100644 src/EasyWindowsApplication/Win32ControlsModule/Backend/Win32UiDefaults.cs

diff --git a/src/EasyWindowsApplication/Core/Application.cs b/src/EasyWindowsApplication/Core/Application.cs
index 0089381..de0e00b 100644
--- a/src/EasyWindowsApplication/Core/Application.cs
+++ b/src/EasyWindowsApplication/Core/Application.cs
@@ -51,6 +51,9 @@ internal void AddWindow(WindowModel window)
 
     public void Initialize()
     {
+        // 1. Registrar defaults PRIMERO (antes de cualquier control o HFONT)
+        try { UiDefaultsProvider.Set(new Win32ControlsModule.Backend.Win32UiDefaults()); } catch { }
+
         var icc = new INITCOMMONCONTROLSEX
         {
             dwSize = (uint)System.Runtime.InteropServices.Marshal.SizeOf<INITCOMMONCONTROLSEX>(),
diff --git a/src/EasyWindowsApplication/Core/Constants.cs b/src/EasyWindowsApplication/Core/Constants.cs
index 2eab93a..bc1b04e 100644
--- a/src/EasyWindowsApplication/Core/Constants.cs
+++ b/src/EasyWindowsApplication/Core/Constants.cs
@@ -92,6 +92,14 @@ internal static class WM
         internal const uint MOUSEWHEEL = 0x020A;
         internal const uint ENTERSIZEMOVE = 0x0231;
         internal const uint EXITSIZEMOVE = 0x0232;
+        internal const uint SETTINGCHANGE = 0x001A;
+        internal const uint DPICHANGED = 0x02E0;
+    }
+
+    internal static class SPI
+    {
+        internal const uint GETNONCLIENTMETRICS = 0x0029;
+        internal const uint SETNONCLIENTMETRICS = 0x002A;
     }
 
     internal static class WMSIZE
diff --git a/src/EasyWindowsApplication/Core/ControlBase.cs b/src/EasyWindowsApplication/Core/ControlBase.cs
index 945648c..393144e 100644
--- a/src/EasyWindowsApplication/Core/ControlBase.cs
+++ b/src/EasyWindowsApplication/Core/ControlBase.cs
@@ -3,6 +3,7 @@
 
 using EasyWindowsApplication.Core.LayoutEngine;
 using EasyWindowsApplication.Share;
+using EasyWindowsApplication.Win32ControlsModule.Backend;
 using EasyWindowsApplication.Win32ControlsModule.Frontend;
 using static EasyWindowsApplication.Core.Win32;
 
@@ -210,14 +211,19 @@ protected string GetWindowText()
         }
     }
 
+    private static nint GetFallbackFont()
+    {
+        try { return ControlProcedures.GetDefaultFont(); } catch { return GetStockObject(17); }
+    }
+
     protected (int Width, int Height) MeasureText(string text)
     {
         if (string.IsNullOrEmpty(text))
             return (20, 24);
 
         nint hdc = GetDC(Hwnd);
-        nint hfont = SendMessageW(Hwnd, WM.GETFONT, 0, 0);
-        nint oldFont = SelectObject(hdc, hfont != 0 ? hfont : GetStockObject(17));
+        nint hfont = Hwnd != 0 ? SendMessageW(Hwnd, WM.GETFONT, 0, 0) : 0;
+        nint oldFont = SelectObject(hdc, hfont != 0 ? hfont : GetFallbackFont());
         RECT rect = default;
         DrawTextW(hdc, text, -1, ref rect, DT.CALCRECT | DT.SINGLELINE);
         SelectObject(hdc, oldFont);
@@ -231,8 +237,8 @@ protected string GetWindowText()
             return (20, 24);
 
         nint hdc = GetDC(Hwnd);
-        nint hfont = SendMessageW(Hwnd, WM.GETFONT, 0, 0);
-        nint oldFont = SelectObject(hdc, hfont != 0 ? hfont : GetStockObject(17));
+        nint hfont = Hwnd != 0 ? SendMessageW(Hwnd, WM.GETFONT, 0, 0) : 0;
+        nint oldFont = SelectObject(hdc, hfont != 0 ? hfont : GetFallbackFont());
 
         GetTextExtentPoint32W(hdc, text, text.Length, out SIZE size);
 
@@ -247,8 +253,8 @@ protected string GetWindowText()
             return (20, 24);
 
         nint hdc = GetDC(Hwnd);
-        nint hfont = SendMessageW(Hwnd, WM.GETFONT, 0, 0);
-        nint oldFont = SelectObject(hdc, hfont != 0 ? hfont : GetStockObject(17));
+        nint hfont = Hwnd != 0 ? SendMessageW(Hwnd, WM.GETFONT, 0, 0) : 0;
+        nint oldFont = SelectObject(hdc, hfont != 0 ? hfont : GetFallbackFont());
 
         int totalWidth = 0;
         int maxHeight = 0;
diff --git a/src/EasyWindowsApplication/Core/HandleRegistry.cs b/src/EasyWindowsApplication/Core/HandleRegistry.cs
index 175c6ef..a684009 100644
--- a/src/EasyWindowsApplication/Core/HandleRegistry.cs
+++ b/src/EasyWindowsApplication/Core/HandleRegistry.cs
@@ -145,4 +145,10 @@ internal void UnregisterWindowByHwnd(nint hwnd)
 
     internal IBaseWindow? GetWindow(string name)
         => _windowByName.TryGetValue(name, out var w) ? w : null;
+
+    internal IEnumerable<nint> AllControlHandles()
+    {
+        foreach (var kv in _hwndToControl)
+            yield return kv.Key;
+    }
 }
diff --git a/src/EasyWindowsApplication/Core/MasterRouter.cs b/src/EasyWindowsApplication/Core/MasterRouter.cs
index ce6eead..7f162f3 100644
--- a/src/EasyWindowsApplication/Core/MasterRouter.cs
+++ b/src/EasyWindowsApplication/Core/MasterRouter.cs
@@ -196,6 +196,36 @@ internal nint WndProc(nint hwnd, uint msg, nint wParam, nint lParam)
                 return 0;
             }
         }
+        else if (msg == WM.SETTINGCHANGE)
+        {
+            // SPI_SETNONCLIENTMETRICS sent when system font/theme changes
+            if ((uint)wParam == SPI.SETNONCLIENTMETRICS)
+            {
+                try { Win32ControlsModule.Backend.ControlProcedures.InvalidateDefaultFont(); } catch { }
+                nint newFont = 0;
+                try { newFont = Win32ControlsModule.Backend.ControlProcedures.GetDefaultFont(); } catch { }
+                if (newFont != 0)
+                {
+                    foreach (var ch in _registry.AllControlHandles())
+                    {
+                        try { Win32.SendMessageW(ch, WM.SETFONT, newFont, 1); } catch { }
+                    }
+                }
+            }
+        }
+        else if (msg == WM.DPICHANGED)
+        {
+            try { Win32ControlsModule.Backend.ControlProcedures.InvalidateDefaultFont(); } catch { }
+            nint newFont = 0;
+            try { newFont = Win32ControlsModule.Backend.ControlProcedures.GetDefaultFont(); } catch { }
+            if (newFont != 0)
+            {
+                foreach (var ch in _registry.AllControlHandles())
+                {
+                    try { Win32.SendMessageW(ch, WM.SETFONT, newFont, 1); } catch { }
+                }
+            }
+        }
 
         if (msg == WM.DESTROY)
         {
diff --git a/src/EasyWindowsApplication/Core/UiDefaults/ControlUiDefaults.cs b/src/EasyWindowsApplication/Core/UiDefaults/ControlUiDefaults.cs
new file mode 100644
index 0000000..0ff3ac6
--- /dev/null
+++ b/src/EasyWindowsApplication/Core/UiDefaults/ControlUiDefaults.cs
@@ -0,0 +1,10 @@
+using EasyWindowsApplication.Share;
+
+namespace EasyWindowsApplication.Core;
+
+internal sealed record ControlUiDefaults
+{
+    public int? PreferredHeight { get; init; }
+    public Thickness? Padding { get; init; }
+    public Color? Background { get; init; }
+}
diff --git a/src/EasyWindowsApplication/Core/UiDefaults/CoreUiDefaults.cs b/src/EasyWindowsApplication/Core/UiDefaults/CoreUiDefaults.cs
new file mode 100644
index 0000000..ac02d89
--- /dev/null
+++ b/src/EasyWindowsApplication/Core/UiDefaults/CoreUiDefaults.cs
@@ -0,0 +1,52 @@
+using EasyWindowsApplication.Share;
+
+namespace EasyWindowsApplication.Core;
+
+internal abstract class CoreUiDefaults : IDefaultUiValues
+{
+    public virtual WindowUiDefaults MainWindow => new()
+    {
+        Width = 420,
+        Height = 280,
+        Position = WindowPositionOnScreen.Center,
+        Background = null
+    };
+
+    public virtual WindowUiDefaults AlternativeWindow => new()
+    {
+        Width = 400,
+        Height = 300,
+        Position = WindowPositionOnScreen.Center,
+        Background = null
+    };
+
+    public abstract FontSpec DefaultFont { get; }
+
+    public virtual Color DefaultForeground
+        => ColorFromSysColor(Win32.GetSysColor(COLOR_WINDOWTEXT));
+
+    public virtual Color DefaultBackground
+        => ColorFromSysColor(Win32.GetSysColor(COLOR_WINDOW));
+
+    public virtual Thickness DefaultPadding => new(3);
+    public virtual int DefaultControlSpacing => 6;
+    public virtual bool EnableVisualStyles => true;
+
+    public virtual IReadOnlyDictionary<Type, ControlUiDefaults> ControlDefaults
+        => _empty;
+
+    private static readonly IReadOnlyDictionary<Type, ControlUiDefaults> _empty
+        = new Dictionary<Type, ControlUiDefaults>();
+
+    protected static Color ColorFromSysColor(int colorRef)
+        => Color.FromRgb(
+            (byte)(colorRef & 0xFF),
+            (byte)((colorRef >> 8) & 0xFF),
+            (byte)((colorRef >> 16) & 0xFF));
+
+    // SysColor indices (winuser.h)
+    private const int COLOR_WINDOW = 5;
+    private const int COLOR_WINDOWTEXT = 8;
+    private const int COLOR_BTNFACE = 15;
+    private const int COLOR_BTNTEXT = 18;
+}
diff --git a/src/EasyWindowsApplication/Core/UiDefaults/DefaultUiValuesExtensions.cs b/src/EasyWindowsApplication/Core/UiDefaults/DefaultUiValuesExtensions.cs
new file mode 100644
index 0000000..1d7ada1
--- /dev/null
+++ b/src/EasyWindowsApplication/Core/UiDefaults/DefaultUiValuesExtensions.cs
@@ -0,0 +1,10 @@
+namespace EasyWindowsApplication.Core;
+
+internal static class DefaultUiValuesExtensions
+{
+    public static ControlUiDefaults? GetFor(this IDefaultUiValues d, Type t)
+        => d.ControlDefaults.TryGetValue(t, out var v) ? v : null;
+
+    public static ControlUiDefaults? GetFor<T>(this IDefaultUiValues d)
+        => d.GetFor(typeof(T));
+}
diff --git a/src/EasyWindowsApplication/Core/UiDefaults/FontSpec.cs b/src/EasyWindowsApplication/Core/UiDefaults/FontSpec.cs
new file mode 100644
index 0000000..7414c18
--- /dev/null
+++ b/src/EasyWindowsApplication/Core/UiDefaults/FontSpec.cs
@@ -0,0 +1,15 @@
+namespace EasyWindowsApplication.Core;
+
+internal enum FontWeight { Normal, Bold }
+internal enum FontStyle { Regular, Italic }
+
+internal sealed record FontSpec
+{
+    public static readonly FontSpec SystemTheme = new() { IsSystemTheme = true };
+
+    public bool IsSystemTheme { get; init; }
+    public string Family { get; init; } = "Segoe UI";
+    public float Size { get; init; } = 9f;
+    public FontWeight Weight { get; init; } = FontWeight.Normal;
+    public FontStyle Style { get; init; } = FontStyle.Regular;
+}
diff --git a/src/EasyWindowsApplication/Core/UiDefaults/IDefaultUiValues.cs b/src/EasyWindowsApplication/Core/UiDefaults/IDefaultUiValues.cs
new file mode 100644
index 0000000..3dfacbf
--- /dev/null
+++ b/src/EasyWindowsApplication/Core/UiDefaults/IDefaultUiValues.cs
@@ -0,0 +1,18 @@
+using EasyWindowsApplication.Share;
+
+namespace EasyWindowsApplication.Core;
+
+internal interface IDefaultUiValues
+{
+    WindowUiDefaults MainWindow { get; }
+    WindowUiDefaults AlternativeWindow { get; }
+
+    FontSpec DefaultFont { get; }
+    Color DefaultForeground { get; }
+    Color DefaultBackground { get; }
+    Thickness DefaultPadding { get; }
+    int DefaultControlSpacing { get; }
+    bool EnableVisualStyles { get; }
+
+    IReadOnlyDictionary<Type, ControlUiDefaults> ControlDefaults { get; }
+}
diff --git a/src/EasyWindowsApplication/Core/UiDefaults/UiDefaultsProvider.cs b/src/EasyWindowsApplication/Core/UiDefaults/UiDefaultsProvider.cs
new file mode 100644
index 0000000..c8fac77
--- /dev/null
+++ b/src/EasyWindowsApplication/Core/UiDefaults/UiDefaultsProvider.cs
@@ -0,0 +1,16 @@
+namespace EasyWindowsApplication.Core;
+
+internal static class UiDefaultsProvider
+{
+    private sealed class CoreFallbackDefaults : CoreUiDefaults
+    {
+        public override FontSpec DefaultFont => FontSpec.SystemTheme;
+    }
+
+    private static IDefaultUiValues _current = new CoreFallbackDefaults();
+
+    public static IDefaultUiValues Current => _current;
+
+    public static void Set(IDefaultUiValues defaults)
+        => _current = defaults ?? throw new ArgumentNullException(nameof(defaults));
+}
diff --git a/src/EasyWindowsApplication/Core/UiDefaults/WindowUiDefaults.cs b/src/EasyWindowsApplication/Core/UiDefaults/WindowUiDefaults.cs
new file mode 100644
index 0000000..ae548fc
--- /dev/null
+++ b/src/EasyWindowsApplication/Core/UiDefaults/WindowUiDefaults.cs
@@ -0,0 +1,13 @@
+using EasyWindowsApplication.Share;
+
+namespace EasyWindowsApplication.Core;
+
+internal sealed record WindowUiDefaults
+{
+    public int Width { get; init; } = 420;
+    public int Height { get; init; } = 280;
+    public WindowPositionOnScreen Position { get; init; } = WindowPositionOnScreen.Center;
+    public Color? Background { get; init; } = null;
+    public string Title { get; init; } = "";
+    public string Name { get; init; } = "";
+}
diff --git a/src/EasyWindowsApplication/Win32ControlsModule/Backend/Controls.cs b/src/EasyWindowsApplication/Win32ControlsModule/Backend/Controls.cs
index c68ced6..3993daa 100644
--- a/src/EasyWindowsApplication/Win32ControlsModule/Backend/Controls.cs
+++ b/src/EasyWindowsApplication/Win32ControlsModule/Backend/Controls.cs
@@ -18,6 +18,29 @@ public string Text
     public bool Enabled { get; set; } = true;
     public void Click() => OnClick(() => { });
     public void SetStyle(uint style, bool redraw = true) { }
+
+    protected override (float Width, float Height) MeasureContent(float availableWidth, float availableHeight)
+    {
+        string text = GetWindowText();
+        var (tw, th) = string.IsNullOrEmpty(text) ? (20, 24) : MeasureTextByGlyphs(text);
+        var defaults = UiDefaultsProvider.Current.GetFor<IButton>();
+        if (defaults == null)
+            defaults = UiDefaultsProvider.Current.GetFor<Button>();
+        float preferredH = defaults?.PreferredHeight ?? 24f;
+        // DPI scaling: defaults are at 96 DPI, scale to current DPI if possible
+        try
+        {
+            uint dpi = 0;
+            if (Hwnd != 0)
+                dpi = Win32Controls.GetDpiForWindow(Hwnd);
+            if (dpi == 0) dpi = Win32Controls.GetDpiForSystem();
+            if (dpi != 0 && dpi != 96)
+                preferredH = preferredH * dpi / 96f;
+        }
+        catch { }
+        // Height is fixed by defaults, width by text
+        return (tw, preferredH);
+    }
 }
 
 public sealed class Label : ControlBase, ILabel
diff --git a/src/EasyWindowsApplication/Win32ControlsModule/Backend/Procedures.cs b/src/EasyWindowsApplication/Win32ControlsModule/Backend/Procedures.cs
index 6eae7be..e85eaf0 100644
--- a/src/EasyWindowsApplication/Win32ControlsModule/Backend/Procedures.cs
+++ b/src/EasyWindowsApplication/Win32ControlsModule/Backend/Procedures.cs
@@ -10,13 +10,81 @@ internal static class ControlProcedures
 
     internal static void SetInstance(nint hInstance) => _hInstance = hInstance;
 
+    internal static void InvalidateDefaultFont()
+    {
+        if (_defaultFont == 0) return;
+        Win32Controls.DeleteObject(_defaultFont);
+        _defaultFont = 0;
+    }
+
     internal static nint GetDefaultFont()
     {
-        if (_defaultFont == 0)
-            _defaultFont = Win32.GetStockObject(17); // DEFAULT_GUI_FONT
+        if (_defaultFont != 0) return _defaultFont;
+
+        var spec = UiDefaultsProvider.Current.DefaultFont;
+
+        if (spec.IsSystemTheme)
+        {
+            var ncm = new NONCLIENTMETRICS
+            {
+                cbSize = (uint)Marshal.SizeOf<NONCLIENTMETRICS>()
+            };
+            if (Win32Controls.SystemParametersInfoW(SPI.GETNONCLIENTMETRICS, ncm.cbSize, ref ncm, 0))
+            {
+                _defaultFont = Win32Controls.CreateFontIndirectW(ref ncm.lfMessageFont);
+                if (_defaultFont != 0) return _defaultFont;
+            }
+        }
+
+        _defaultFont = CreateFontFromSpec(spec);
         return _defaultFont;
     }
 
+    private static nint CreateFontFromSpec(FontSpec spec)
+    {
+        var lf = new LOGFONT
+        {
+            lfHeight = -(int)(spec.Size * GetDpiForSystemSafe() / 72f),
+            lfWeight = spec.Weight == FontWeight.Bold ? 700 : 400,
+            lfItalic = spec.Style == FontStyle.Italic ? (byte)1 : (byte)0,
+            lfCharSet = 1, // DEFAULT_CHARSET
+            lfQuality = 5, // CLEARTYPE_QUALITY
+            lfFaceName = spec.Family ?? "Segoe UI"
+        };
+        var h = Win32Controls.CreateFontIndirectW(ref lf);
+        if (h != 0) return h;
+        // Ultimate fallback: GetStockObject DEFAULT_GUI_FONT (17)
+        return Win32Controls.GetStockObject(17);
+    }
+
+    private static int GetDpiForSystemSafe()
+    {
+        try { return (int)Win32Controls.GetDpiForSystem(); } catch { }
+        try
+        {
+            nint hdc = Win32Controls.GetDC(0);
+            if (hdc != 0)
+            {
+                int dpi = Win32Controls.GetDeviceCaps(hdc, LOGPIXELS.LOGPIXELSY);
+                Win32Controls.ReleaseDC(0, hdc);
+                if (dpi > 0) return dpi;
+            }
+        }
+        catch { }
+        return 96;
+    }
+
+    private static int GetDpiForWindowSafe(nint hwnd)
+    {
+        try
+        {
+            uint dpi = Win32Controls.GetDpiForWindow(hwnd);
+            if (dpi != 0) return (int)dpi;
+        }
+        catch { }
+        return GetDpiForSystemSafe();
+    }
+
     internal static nint CreateControl(
         string windowClass,
         nint parentHwnd,
diff --git a/src/EasyWindowsApplication/Win32ControlsModule/Backend/Win32.cs b/src/EasyWindowsApplication/Win32ControlsModule/Backend/Win32.cs
index 73fe7d7..39a9152 100644
--- a/src/EasyWindowsApplication/Win32ControlsModule/Backend/Win32.cs
+++ b/src/EasyWindowsApplication/Win32ControlsModule/Backend/Win32.cs
@@ -25,4 +25,85 @@ internal static partial nint CreateWindowExW(
 
     [LibraryImport("kernel32.dll")]
     internal static partial nint GetModuleHandleW(nint lpModuleName);
+
+    [LibraryImport("gdi32.dll")]
+    internal static partial nint GetStockObject(int fnObject);
+
+    [LibraryImport("gdi32.dll")]
+    [return: MarshalAs(UnmanagedType.Bool)]
+    internal static partial bool DeleteObject(nint hObject);
+
+    [DllImport("gdi32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
+    internal static extern nint CreateFontIndirectW(ref LOGFONT lplf);
+
+    [DllImport("user32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
+    [return: MarshalAs(UnmanagedType.Bool)]
+    internal static extern bool SystemParametersInfoW(uint uiAction, uint uiParam, ref NONCLIENTMETRICS pvParam, uint fWinIni);
+
+    [LibraryImport("user32.dll")]
+    internal static partial uint GetDpiForWindow(nint hwnd);
+
+    [LibraryImport("user32.dll")]
+    internal static partial uint GetDpiForSystem();
+
+    [LibraryImport("gdi32.dll")]
+    internal static partial int GetDeviceCaps(nint hdc, int nIndex);
+
+    [LibraryImport("user32.dll")]
+    internal static partial nint GetDC(nint hWnd);
+
+    [LibraryImport("user32.dll")]
+    internal static partial int ReleaseDC(nint hWnd, nint hDC);
+}
+
+[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
+internal struct LOGFONT
+{
+    public int lfHeight;
+    public int lfWidth;
+    public int lfEscapement;
+    public int lfOrientation;
+    public int lfWeight;
+    public byte lfItalic;
+    public byte lfUnderline;
+    public byte lfStrikeOut;
+    public byte lfCharSet;
+    public byte lfOutPrecision;
+    public byte lfClipPrecision;
+    public byte lfQuality;
+    public byte lfPitchAndFamily;
+    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
+    public string lfFaceName;
+}
+
+[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
+internal struct NONCLIENTMETRICS
+{
+    public uint cbSize;
+    public int iBorderWidth;
+    public int iScrollWidth;
+    public int iScrollHeight;
+    public int iCaptionWidth;
+    public int iCaptionHeight;
+    public LOGFONT lfCaptionFont;
+    public int iSmCaptionWidth;
+    public int iSmCaptionHeight;
+    public LOGFONT lfSmCaptionFont;
+    public int iMenuWidth;
+    public int iMenuHeight;
+    public LOGFONT lfMenuFont;
+    public LOGFONT lfStatusFont;
+    public LOGFONT lfMessageFont;
+    // Windows Vista+ adds iPaddedBorderWidth but we omit for compatibility; cbSize controls it
+}
+
+internal static class SPI
+{
+    internal const uint GETNONCLIENTMETRICS = 0x0029;
+    internal const uint SETNONCLIENTMETRICS = 0x002A;
+}
+
+internal static class LOGPIXELS
+{
+    internal const int LOGPIXELSY = 90;
 }
diff --git a/src/EasyWindowsApplication/Win32ControlsModule/Backend/Win32UiDefaults.cs b/src/EasyWindowsApplication/Win32ControlsModule/Backend/Win32UiDefaults.cs
new file mode 100644
index 0000000..3ab50f4
--- /dev/null
+++ b/src/EasyWindowsApplication/Win32ControlsModule/Backend/Win32UiDefaults.cs
@@ -0,0 +1,19 @@
+using EasyWindowsApplication.Core;
+using EasyWindowsApplication.Share;
+using EasyWindowsApplication.Win32ControlsModule.Frontend;
+
+namespace EasyWindowsApplication.Win32ControlsModule.Backend;
+
+internal sealed class Win32UiDefaults : CoreUiDefaults
+{
+    public override FontSpec DefaultFont => FontSpec.SystemTheme;
+
+    public override IReadOnlyDictionary<Type, ControlUiDefaults> ControlDefaults { get; } =
+        new Dictionary<Type, ControlUiDefaults>
+        {
+            [typeof(IButton)] = new ControlUiDefaults { PreferredHeight = 30, Padding = new Thickness(10, 0) },
+            [typeof(ILabel)] = new ControlUiDefaults { PreferredHeight = 23 },
+            [typeof(Button)] = new ControlUiDefaults { PreferredHeight = 30, Padding = new Thickness(10, 0) },
+            [typeof(Label)] = new ControlUiDefaults { PreferredHeight = 23 },
+        };
+}