title: Sending BM_CLICK message to Windows 10 application not working
body: <p>I have an installation dialog (made with nsis) that has two buttons (install and cancel). I'm trying to write automated tests for the install process using low level win32 api. To click on the button(s) I use the following code:</p>
  
  <pre><code>char windowName[] = "Desktop Application Setup";
  char cancelButtonText[] = "Cancel";
  
  HWND hWndMainWindow = NULL;
  HWND hButton = NULL;
  
  hWndMainWindow = FindWindow(NULL, windowName);
  if (hWndMainWindow)
  {
      hButton = FindWindowEx(hWndMainWindow, NULL, NULL, cancelButtonText);
      if (hButton)
      {
          SendMessage(hButton, BM_CLICK, 0, 0);
      }
  }
  </code></pre>
  
  <p>On Windows 7, this works perfectly. On Windows 10, it simply does nothing. It finds the button, it sends the message, but the click just doesn't happen.</p>
  
  <p>Is this some security thing introduced in Windows 10? Is it a known issue?</p>