How can I be notified when a new window is created on Win32?

Question

Is there a way using Win32, to register for notifications when a new window is created. I'm trying to keep a list of current open windows, but am now just polling the list of current windows using EnumWindows().

Anyone done something similar?

Thanks

Answer 1

Use SetWindowsHookEx to set up a WH_SHELL hook and look for the HSHELL_WINDOWCREATED event.

Answer 2

Sure - you can write a CBT hook and watch for HCBT_CREATEWND. See also SetWindowsHookEx().

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Note that this will allow you to be notified of all window creation, before the windows being created are even fully initialized. If all you need are unowned, top-level windows, RichieHindle's suggestion may work better...

Answer 3

Detours will permit you to attach hooks to arbitrary Win32 functions. However, polling is probably a more reliable way to approach the problem: you don't have to worry about whether you've missed a particular window-creation method (how many are there in Win32? I bet more than one!), and, of course, you won't be rewriting the machine code for windows functions at runtime.

But, you know, your call.

Answer 4

I'm not sure if I'm doing this right, but I'm not able to get the SetWindowsHookEx method to fire.

anything come to mind?

here is my snip

[DllImport("user32.dll", SetLastError = true)]
        private static extern IntPtr SetWindowsHookEx(HookType hook, HookProc callback, IntPtr hMod, uint dwThreadId);
        [DllImport("user32.dll")]
        private static extern int CallNextHookEx(IntPtr hhk, int nCode, IntPtr wParam, IntPtr lParam);
        const int HSHELL_WINDOWCREATED = 1;

        private static HookProc winDelegate = ShellHookProcDelegate;
        internal static void RegisterWindowCreatedEvent()
        {
            SetWindowsHookEx(HookType.WH_SHELL, winDelegate, IntPtr.Zero, 0);
        }
        private static int ShellHookProcDelegate(int code, IntPtr wParam, IntPtr lParam)
        {
            if (code != HSHELL_WINDOWCREATED)
            {
                return CallNextHookEx(IntPtr.Zero, code, wParam, lParam);
            }

//App specific code here

            return CallNextHookEx(IntPtr.Zero, code, wParam, lParam);
        }

Answer 5

You could try WinEventHook library for autohotkey. Try modifying the notepad popup blocker example with the following:

HookProc( hWinEventHook, Event, hWnd, idObject, idChild, dwEventThread, dwmsEventTime ) { if Event ; EVENT_SYSTEM_FOREGROUND = 0x3 {
WinGetTitle, title, ahk_id %hWnd% If (title = "your_window_name" msgbox, your window has been created } }