Question

I’m trying to send a keystroke to another application. I can successfully find the window handle since using SendMessage worked exactly as intended.

However, when I switched the SendMessage over to PostMessage, the application no longer received the messages.

I did, however, find a workaround by using HWND_BROADCAST as the window handle, and it works fine, but isn’t the ideal way to go about it.

What I’m asking is, I have a valid hWnd, how can I send it messages using PostMessage and not SendMessage?

Edit
This is what I’m trying to do.

HWND Target = FindWindow(0, "Window Title Goes Here");
LPARAM lParam = (1 | (57<<16)); // OEM Code and Repeat for WM_KEYDOWN
WPARAM wParam = VK_SPACE;
PostMessage(HWND_BROADCAST, WM_KEYDOWN, wParam, lParam); // Works
PostMessage(Target, WM_KEYDOWN, wParam, lParam); // Doesn't Work
SendMessage(Target, WM_KEYDOWN, wParam, lParam); // Works, but I need Post

Answer 1

The PostMessage function does not work when the message numbers between 0 and WM_USER-1. Use RegisterWindowMessage function to register your own messages.