Blocking windows hotkeys in an application

Question

I'm creating a C++ application wherein I need to programmatically block several windows hotkeys. I'm using SetWindowsHook() and lowlevelkeyboardproc() winapi calls. But just returning a non-zero value for the hook does not block the following keys. 1) Windows key + L 2) Windows Key + alt + R 3) Windows key + G 4) Windows key + K and a few more sequences with windows key. I have tried several ways but none of them seem to work. So I wanted to know if it is not possible to override the system hotkeys in Windows 7 and Windows 10. Help much appreciated!

Answer 1

Some keys combinations cannot be intercepted by a LL Keyboard Hook

But they can be disabled with Registry.

For example :

Windows Key + L :

HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System

DisableLockWorkstation = 1

Windows Key + G ( + Windows Key + Alt + R and other shortcuts for Xbox Game Bar)

HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\GameDVR

AppCaptureEnabled = 0

Answer 2

Hello Ash,

Thank you for your question and for reaching out with your question today.

Please see the code example below that uses a system-wide hook without the need for DLL interaction:

LRESULT CALLBACK LowLevelKeyboardProc(int nCode, WPARAM wParam, LPARAM lParam)
{
if (nCode < 0)
    return CallNextHookEx(NULL, nCode, wParam, lParam);

tagKBDLLHOOKSTRUCT *str = (tagKBDLLHOOKSTRUCT *)lParam;

switch(str->flags)
{
    case (LLKHF_ALTDOWN):
        qDebug() << "ALT";
        delete str;
    return 1;
}

if (wParam == WM_KEYDOWN)
{
    switch (str->vkCode)
    {
        case VK_RWIN:
        case VK_LWIN:
        case VK_LCONTROL:
        case VK_RCONTROL:
        case VK_APPS:
        case VK_SLEEP:
        case VK_MENU:
            qDebug() << "SPECIAL PRESS";
            delete str;
        return 1;
    }
}

return CallNextHookEx(NULL, nCode, wParam, lParam);
}

It blocks inputs of Ctrl, Windows Key and Alt.

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