Hacking FontDialog

using System;
using System.IO;
using System.Text;
using System.Data;
using System.Drawing;
using System.Threading;
using System.Windows.Forms;
using System.ComponentModel;
using System.Collections.Generic;
using System.Runtime.InteropServices;

namespace DrawTools
{
    public partial class FontDialogEx : UserControl
    {
        private const SetWindowPosFlags UFLAGSHIDE =
            SetWindowPosFlags.SWP_NOACTIVATE |
            SetWindowPosFlags.SWP_NOOWNERZORDER |
            SetWindowPosFlags.SWP_NOMOVE |
            SetWindowPosFlags.SWP_NOSIZE |
            SetWindowPosFlags.SWP_HIDEWINDOW;

        public FontDialogEx()
        {
            InitializeComponent();
        }

        public FontDialog FontDialog
        {
            get { return dlgFont; }
        }

        public DialogResult ShowDialog()
        {
            return ShowDialog(null);
        }

        public DialogResult ShowDialog(IWin32Window owner)
        {
            DialogResult returnDialogResult = DialogResult.Cancel;
            DummyForm form = new DummyForm(this);
            form.Show(owner);
            Win32.SetWindowPos(form.Handle, IntPtr.Zero, 0, 0, 0, 0, UFLAGSHIDE);
            form.WatchForActivate = true;
            try
            {
                returnDialogResult = dlgFont.ShowDialog(form);
            }
            // Sometimes if you open a animated .gif on the preview and the Form is closed, .Net class throw an exception
            // Lets ignore this exception and keep closing the form.
            catch (Exception) { }
            form.Close();
            return returnDialogResult;
        }

        private class FontDialogNative : NativeWindow, IDisposable
        {
            private IntPtr mFontDialogHandle;
            private BaseDialogNative mBaseDialogNative;
            private FontDialogEx mSourceControl;

            public FontDialogNative(IntPtr handle, FontDialogEx sourceControl)
            {
                mFontDialogHandle = handle;
                mSourceControl = sourceControl;
                AssignHandle(mFontDialogHandle);

                //hide unneeded components
                Win32.ShowWindow(Win32.GetDlgItem(mFontDialogHandle, 1090), Win32.SW_HIDE);
                Win32.ShowWindow(Win32.GetDlgItem(mFontDialogHandle, 1138), Win32.SW_HIDE);
            }

            public void Dispose()
            {
                ReleaseHandle();
                if (mBaseDialogNative != null)
                {
                    mBaseDialogNative.Dispose();
                }
            }

            private void PopulateWindowsHandlers()
            {
                Win32.EnumChildWindows(mFontDialogHandle, new Win32.EnumWindowsCallBack(OpenFileDialogEnumWindowCallBack), 0);
            }

            private bool OpenFileDialogEnumWindowCallBack(IntPtr hwnd, int lParam)
            {
                StringBuilder className = new StringBuilder(256);
                Win32.GetClassName(hwnd, className, className.Capacity);

                // Dialog Window
                if (className.ToString().StartsWith("#32770"))
                {
                    mBaseDialogNative = new BaseDialogNative(hwnd);
                    return true;
                }
                return true;
            }
        }

        private class BaseDialogNative : NativeWindow, IDisposable
        {
            private IntPtr mHandle;

            public BaseDialogNative(IntPtr handle)
            {
                mHandle = handle;
                AssignHandle(handle);
            }

            public void Dispose()
            {
                ReleaseHandle();
            }
        }

        private class DummyForm : Form
        {
            private FontDialogNative mNativeDialog = null;
            private FontDialogEx mFileDialogEx = null;
            private bool mWatchForActivate = false;
            private IntPtr mFontDialogHandle = IntPtr.Zero;

            public DummyForm(FontDialogEx fileDialogEx)
            {
                mFileDialogEx = fileDialogEx;
                this.Text = "";
                this.StartPosition = FormStartPosition.Manual;
                this.Location = new Point(-32000, -32000);
                this.ShowInTaskbar = false;
            }

            public bool WatchForActivate
            {
                get { return mWatchForActivate; }
                set { mWatchForActivate = value; }
            }

            protected override void OnClosing(CancelEventArgs e)
            {
                if (mNativeDialog != null)
                    mNativeDialog.Dispose();
                base.OnClosing(e);
            }

            protected override void WndProc(ref Message m)
            {
                if (mWatchForActivate && m.Msg == (int)Win32.WM_ACTIVATE)
                {
                    mWatchForActivate = false;
                    mFontDialogHandle = m.LParam;
                    mNativeDialog = new FontDialogNative(m.LParam, mFileDialogEx);
                }
                base.WndProc(ref m);
            }
        }
    }
}