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I want to send keystrokes to window that is not focused. To another application.
Can you show me some tutorials or, tell me how.

Why doing so?

I found this, but I don't know how where to found the key codes for "WM_KEYDOWN", do you know a list of all the keys transformed for "WM_KEYDOWN"?

[DllImport("User32.Dll", EntryPoint = "PostMessageA", SetLastError = true)]
public static extern bool PostMessage(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam);

PostMessage(winHandle, (uint)WM_KEYDOWN, (IntPtr)66, IntPtr.Zero);
Basically, this is a bad idea. It depends on the application to be "controlled" this way. You cannot just use SendInput, so you need to rely on some message processing using HWND and P/Invoked SendMessage/PostMessage without reliable results.

If this is your application and you want to use this method just for UI development, this is all wrong: you can always use "legal" programming method. If not, any results are not reliable. There is a good principle: develop software, not integrate. And this is certainly not a good method of "integration".

Perhaps, explain you ultimate goals to get a chance to get some positive advice.

Mitran Stefanita Alexandru 21-Nov-11 3:38am
I have to do that same thing every day, and I thought that I can make a small C# program to do that thing for me and save me of some time, I'm not doing this to sell the application or something like that, I just want to help my work. Can you make me a small code to send a message to notepad, when the notepad is not a foreground window. Pleas, it could really help me.

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