Show touch keyboard (TabTip.exe) in Windows 10 Anniversary edition

OK, I reverse engineered what explorer does when the user presses that button in the system tray.

Basically it creates an instance of an undocumented interface ITipInvocation and calls its Toggle(HWND) method, passing desktop window as an argument. As the name suggests, the method either shows or hides the keyboard depending on its current state.

Please note that explorer creates an instance of ITipInvocation on every button click. So I believe the instance should not be cached. I also noticed that explorer never calls Release() on the obtained instance. I'm not too familiar with COM, but this looks like a bug.

I tested this in Windows 8.1, Windows 10 & Windows 10 Anniversary Edition and it works perfectly. Here's a minimal example in C that obviously lacks some error checks.

#include <initguid.h>#include <Objbase.h>#pragma hdrstop// 4ce576fa-83dc-4F88-951c-9d0782b4e376DEFINE_GUID(CLSID_UIHostNoLaunch,    0x4CE576FA, 0x83DC, 0x4f88, 0x95, 0x1C, 0x9D, 0x07, 0x82, 0xB4, 0xE3, 0x76);// 37c994e7_432b_4834_a2f7_dce1f13b834bDEFINE_GUID(IID_ITipInvocation,    0x37c994e7, 0x432b, 0x4834, 0xa2, 0xf7, 0xdc, 0xe1, 0xf1, 0x3b, 0x83, 0x4b);struct ITipInvocation : IUnknown{    virtual HRESULT STDMETHODCALLTYPE Toggle(HWND wnd) = 0;};int WinMain(HINSTANCE hInst, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow){    HRESULT hr;    hr = CoInitialize(0);    ITipInvocation* tip;    hr = CoCreateInstance(CLSID_UIHostNoLaunch, 0, CLSCTX_INPROC_HANDLER | CLSCTX_LOCAL_SERVER, IID_ITipInvocation, (void**)&tip);    tip->Toggle(GetDesktopWindow());    tip->Release();    return 0;}

Here's the C# version as well:

class Program{    static void Main(string[] args)    {        var uiHostNoLaunch = new UIHostNoLaunch();        var tipInvocation = (ITipInvocation)uiHostNoLaunch;        tipInvocation.Toggle(GetDesktopWindow());        Marshal.ReleaseComObject(uiHostNoLaunch);    }    [ComImport, Guid("4ce576fa-83dc-4F88-951c-9d0782b4e376")]    class UIHostNoLaunch    {    }    [ComImport, Guid("37c994e7-432b-4834-a2f7-dce1f13b834b")]    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]    interface ITipInvocation    {        void Toggle(IntPtr hwnd);    }    [DllImport("user32.dll", SetLastError = false)]    static extern IntPtr GetDesktopWindow();}

Update: per @EugeneK comments, I believe that tabtip.exe is the COM server for the COM component in question, so if your code gets REGDB_E_CLASSNOTREG, it should probably run tabtip.exe and try again.

I had the same problem too. It took me much time and headache, but Thanks to Alexei and Torvin I finally got it working on Win 10 1709. Visibility check was the difficulty. Maybe The OSKlib Nuget could be updated. Let me sum up the complete sulotion (For sure my code has some unnecessary lines now):

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Diagnostics;using System.ComponentModel;using Osklib.Interop;using System.Runtime.InteropServices;using System.Threading;namespace OSK{    public static class OnScreenKeyboard    {        static OnScreenKeyboard()        {            var version = Environment.OSVersion.Version;            switch (version.Major)            {                case 6:                    switch (version.Minor)                    {                        case 2:                            // Windows 10 (ok)                            break;                    }                    break;                default:                    break;            }        }        private static void StartTabTip()        {            var p = Process.Start(@"C:\Program Files\Common Files\Microsoft Shared\ink\TabTip.exe");            int handle = 0;            while ((handle = NativeMethods.FindWindow("IPTIP_Main_Window", "")) <= 0)            {                Thread.Sleep(100);            }        }        public static void ToggleVisibility()        {            var type = Type.GetTypeFromCLSID(Guid.Parse("4ce576fa-83dc-4F88-951c-9d0782b4e376"));            var instance = (ITipInvocation)Activator.CreateInstance(type);            instance.Toggle(NativeMethods.GetDesktopWindow());            Marshal.ReleaseComObject(instance);        }        public static void Show()        {            int handle = NativeMethods.FindWindow("IPTIP_Main_Window", "");            if (handle <= 0) // nothing found            {                StartTabTip();                                Thread.Sleep(100);                            }            // on some devices starting TabTip don't show keyboard, on some does  ¯\_(ツ)_/¯            if (!IsOpen())            {                ToggleVisibility();            }        }        public static void Hide()        {            if (IsOpen())            {                ToggleVisibility();            }        }                public static bool Close()        {            // find it            int handle = NativeMethods.FindWindow("IPTIP_Main_Window", "");            bool active = handle > 0;            if (active)            {                // don't check style - just close                NativeMethods.SendMessage(handle, NativeMethods.WM_SYSCOMMAND, NativeMethods.SC_CLOSE, 0);            }            return active;        }        public static bool IsOpen()        {            return GetIsOpen1709() ?? GetIsOpenLegacy();        }        [DllImport("user32.dll", SetLastError = false)]        private static extern IntPtr FindWindowEx(IntPtr parent, IntPtr after, string className, string title = null);        [DllImport("user32.dll", SetLastError = false)]        private static extern uint GetWindowLong(IntPtr wnd, int index);        private static bool? GetIsOpen1709()        {            // if there is a top-level window - the keyboard is closed            var wnd = FindWindowEx(IntPtr.Zero, IntPtr.Zero, WindowClass1709, WindowCaption1709);            if (wnd != IntPtr.Zero)                return false;            var parent = IntPtr.Zero;            for (;;)            {                parent = FindWindowEx(IntPtr.Zero, parent, WindowParentClass1709);                if (parent == IntPtr.Zero)                    return null; // no more windows, keyboard state is unknown                // if it's a child of a WindowParentClass1709 window - the keyboard is open                wnd = FindWindowEx(parent, IntPtr.Zero, WindowClass1709, WindowCaption1709);                if (wnd != IntPtr.Zero)                    return true;            }        }        private static bool GetIsOpenLegacy()        {            var wnd = FindWindowEx(IntPtr.Zero, IntPtr.Zero, WindowClass);            if (wnd == IntPtr.Zero)                return false;            var style = GetWindowStyle(wnd);            return style.HasFlag(WindowStyle.Visible)                && !style.HasFlag(WindowStyle.Disabled);        }        private const string WindowClass = "IPTip_Main_Window";        private const string WindowParentClass1709 = "ApplicationFrameWindow";        private const string WindowClass1709 = "Windows.UI.Core.CoreWindow";        private const string WindowCaption1709 = "Microsoft Text Input Application";        private enum WindowStyle : uint        {            Disabled = 0x08000000,            Visible = 0x10000000,        }        private static WindowStyle GetWindowStyle(IntPtr wnd)        {            return (WindowStyle)GetWindowLong(wnd, -16);        }    }    [ComImport]    [Guid("37c994e7-432b-4834-a2f7-dce1f13b834b")]    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]    interface ITipInvocation    {        void Toggle(IntPtr hwnd);    }    internal static class NativeMethods    {        [DllImport("user32.dll", EntryPoint = "FindWindow")]        internal static extern int FindWindow(string lpClassName, string lpWindowName);        [DllImport("user32.dll", EntryPoint = "SendMessage")]        internal static extern int SendMessage(int hWnd, uint Msg, int wParam, int lParam);        [DllImport("user32.dll", EntryPoint = "GetDesktopWindow", SetLastError = false)]        internal static extern IntPtr GetDesktopWindow();        [DllImport("user32.dll", EntryPoint = "GetWindowLong")]        internal static extern int GetWindowLong(int hWnd, int nIndex);        internal const int GWL_STYLE = -16;        internal const int GWL_EXSTYLE = -20;                internal const int WM_SYSCOMMAND = 0x0112;        internal const int SC_CLOSE = 0xF060;        internal const int WS_DISABLED = 0x08000000;        internal const int WS_VISIBLE = 0x10000000;    }}

The only solution I've found to work is by sending PostMessage as you've mentioned in answer 1. Here's the C# version of it in case someone needs it.

[DllImport("user32.dll", CharSet = CharSet.Unicode)]    private static extern IntPtr FindWindow(string sClassName, string sAppName);[DllImport("user32.dll", CharSet = CharSet.Unicode)]    static extern IntPtr FindWindowEx(IntPtr parentHandle, IntPtr childAfter, string lclassName, string windowTitle); [DllImport("User32.Dll", EntryPoint = "PostMessageA")]    static extern bool PostMessage(IntPtr hWnd, uint msg, int wParam, int lParam);var trayWnd = FindWindow("Shell_TrayWnd", null);var nullIntPtr = new IntPtr(0);if (trayWnd != nullIntPtr){    var trayNotifyWnd = FindWindowEx(trayWnd, nullIntPtr, "TrayNotifyWnd", null);    if (trayNotifyWnd != nullIntPtr)    {        var tIPBandWnd = FindWindowEx(trayNotifyWnd, nullIntPtr, "TIPBand", null);        if (tIPBandWnd != nullIntPtr)        {            PostMessage(tIPBandWnd, (UInt32)WMessages.WM_LBUTTONDOWN, 1, 65537);            PostMessage(tIPBandWnd, (UInt32)WMessages.WM_LBUTTONUP, 1, 65537);        }    }}public enum WMessages : int{    WM_LBUTTONDOWN = 0x201,    WM_LBUTTONUP = 0x202,    WM_KEYDOWN = 0x100,    WM_KEYUP = 0x101,    WH_KEYBOARD_LL = 13,    WH_MOUSE_LL = 14,}