C# and SendMessage (keys) is not working

Question

I tried to send a key to an application. For an easy test I just used notepad. That\'s what the code looks like:

[DllImport(\"USER32.DLL\", EntryPoint = \"Se         


        

Answer 1

Several problems:

• Your declaration is wrong, the last 2 parameters are IntPtr, not int
• You should use PostMessage, not SendMessage
• You are sending to the wrong window. The edit window of Notepad is a child window
• You are forgetting to send WM_KEYUP
• The actual letter you get will depend on the state of the Shift key

The neck shot: Vista and Win7 UIPI (User Interface Privilege Isolation) prevents a restricted process from injecting messages into an elevated process.