Minimize a borderless form by Win + M windows shortcut

user_12205168 0
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The standard Win + M keyboard shortcut minimizes open windows, but it does not minimize a borderless form.

I'm thinking of capturing key events of Win + M in KeyDown event but no luck, since it does not capture both but only captures the first key.

I can't programmatically minimize it using a keyboard shortcut

Any idea on how to minimize my for form by keyboard shortcut? or can I capture Win + M to trigger minimize function?

I'm using borderless form. To reproduce the problem, create a Form and set its BorderStyle to None and run the application. When you press Win + M, all the windows minimize, but my borderless form stays normal.

winforms .net c#
2 Answers

As an option you can enable system menu (having minimize window style) for your borderless form, then while it doesn't show the control box, but the minimize command will work as expected.

Add the following piece of code to your Form and then Win + M will work as expected:

private const int WS_SYSMENU = 0x80000;
private const int WS_MINIMIZEBOX = 0x20000;
protected override CreateParams CreateParams
{
    get
    {
        CreateParams p = base.CreateParams;
        p.Style = WS_SYSMENU | WS_MINIMIZEBOX;
        return p;
    }
}
user_31108340

As a totally different option you can register a low level keyboard hook using SetWindowsHookEx and check if you received the Win + M, then minimize the window and let the key goes through other windows.

Add the following piece of code to your Form and then Win + M will work as expected:

private const int WH_KEYBOARD_LL = 13;
[StructLayout(LayoutKind.Sequential)]
private struct KBDLLHOOKSTRUCT
{
    public Keys vkCode;
    public int scanCode;
    public int flags;
    public int time;
    public IntPtr dwExtraInfo;
}
private delegate IntPtr HookProc(int code, IntPtr wParam, IntPtr lParam);
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr SetWindowsHookEx(
    int idHook, HookProc lpfn, IntPtr hmod, uint dwThreadId);

[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr CallNextHookEx(
    IntPtr hhk, int nCode, IntPtr wParam, IntPtr lParam);

[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr GetModuleHandle(string lpModuleName);

[DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling = true)]
private static extern short GetKeyState(int keyCode);
private const int KEY_PRESSED = 0x8000;
private static bool IsKeyDown(Keys key)
{
    return Convert.ToBoolean(GetKeyState((int)key) & KEY_PRESSED);
}

private IntPtr ptrHook;
private HookProc hookProc;
private IntPtr CaptureKeys(int code, IntPtr wParam, IntPtr lParam)
{
    if (code >= 0)
    {
        KBDLLHOOKSTRUCT objKeyInfo = 
            (KBDLLHOOKSTRUCT)Marshal.PtrToStructure(
                lParam, typeof(KBDLLHOOKSTRUCT));
        if (objKeyInfo.vkCode == (Keys.M) &&
            (IsKeyDown(Keys.LWin) || IsKeyDown(Keys.RWin)))
        {
            this.WindowState = FormWindowState.Minimized;
            return (IntPtr)0;
        }
    }
    return CallNextHookEx(ptrHook, code, wParam, lParam);
}
bool HasAltModifier(int flags)
{
    return (flags & 0x20) == 0x20;
}
protected override void OnLoad(EventArgs e)
{
    base.OnLoad(e);
    var module = Process.GetCurrentProcess().MainModule;
    hookProc = new HookProc(CaptureKeys);
    ptrHook = SetWindowsHookEx(
        WH_KEYBOARD_LL, hookProc, GetModuleHandle(module.ModuleName), 0);
}
user_31108340
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