How Can I Reliably Send Keys to a Background Application Like Notepad?

Sending Keys to Background Applications

The provided code attempts to send the "k" key to Notepad but encounters an issue. To resolve this, several aspects of the code need to be addressed.

Correct Process Handling:

The code assumes that Notepad is already running. To handle this accurately, you should obtain the first Notepad process using:

Process p = Process.GetProcessesByName("notepad").FirstOrDefault();

If Notepad is not currently running, you can initiate it using:

Process p = Process.Start("notepad.exe");

Bring Notepad to Foreground:

Once you have the Notepad process, you need to bring its main window to the foreground:

IntPtr h = p.MainWindowHandle;
SetForegroundWindow(h);

Waiting for Input Stability:

Before sending keys, you should wait for the application to stabilize its input loop:

p.WaitForInputIdle();

Send Key:

Finally, you can send the desired key:

SendKeys.SendWait("k");

Possible Issue with Administrator Rights:

It's worth mentioning that if Notepad is running as Administrator and your application is not, this method may not work.

Modified Code:

Here's the modified code that incorporates the necessary fixes:

[DllImport("User32.dll")]
static extern int SetForegroundWindow(IntPtr point);

Process p = Process.GetProcessesByName("notepad").FirstOrDefault();
if (p != null)
{
    IntPtr h = p.MainWindowHandle;
    SetForegroundWindow(h);
    SendKeys.SendWait("k");
}
else
{
    p = Process.Start("notepad.exe");
    p.WaitForInputIdle();
    IntPtr h = p.MainWindowHandle;
    SetForegroundWindow(h);
    SendKeys.SendWait("k");
}

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