title: C++ SendMessage / PostMessage WM_KEYDOWN WM_KEYUP doesn't work
body: <p>I'm attempting to press the Left arrow key button and Right arrow key button.<br>
  The Window Handle I'm passing in is correct. (see screenshot below)</p>
  
  <p>I used Microsoft Spy++ to figure out the correct PostMessage when I press Left/Right keys.</p>
  
  <p>Here are the screenshots showing the <code>lParam</code> and <code>WParam</code></p>
  
  <p>First 2 screenshots are <code>VK_RIGHT</code> (<code>WM_KEYDOWN</code> &amp; <code>WM_KEYUP</code>)<br>
  Next 2 screenshots are <code>VK_LEFT</code> (<code>WM_KEYDOWN</code> &amp; <code>WM_KEYUP</code>)</p>
  
  <p><img src="https://i.stack.imgur.com/KTQ45.png" alt="postmessage 1">
  <img src="https://i.stack.imgur.com/fz2ow.png" alt="postmessage 2">
  <img src="https://i.stack.imgur.com/OATXQ.png" alt="postmessage 3">
  <img src="https://i.stack.imgur.com/VtBy6.png" alt="postmessage 4"></p>
  
  <p>Here is the code I attempted to use it works by pressing <code>NUMPAD1,2,3</code> to test out whether or not the <code>VK_LEFT</code> OR <code>VK_RIGHT</code> works.. (none of them work).</p>
  
  <pre><code>gKey(VK_NUMPAD1) //crap testing
          {
              windowHandle = FindWindow(L"SSClientMainWndClass", NULL);
              printf("window handle = %x\n", windowHandle);
              PostMessage(windowHandle, WM_KEYDOWN, VK_RIGHT, 0x414D0001);
              //Sleep(1000);
              PostMessage(windowHandle, WM_KEYUP, VK_RIGHT, 0xC14D0001);
              Sleep(1000);
  
          }
  gKey(VK_NUMPAD2) //crap testing
          {
              windowHandle = FindWindow(L"SSClientMainWndClass", NULL);
              printf("window handle = %x\n", windowHandle);
              PostMessage(windowHandle, WM_KEYDOWN, VK_LEFT, 0x414B0001);
              Sleep(1000);
              PostMessage(windowHandle, WM_KEYUP, VK_LEFT, 0xC14B0001);
              Sleep(1000);
          }
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/6FeBn.png" alt="code"></p>
  
  <p>Here are the screenshots of pressing the <code>VK_NUMPAD1</code> in the game. (The Post message is sent to the correct Window and the information seems correct!)
  <img src="https://i.stack.imgur.com/WeBbj.png" alt="[postmessage 1">
  <img src="https://i.stack.imgur.com/xsf4l.png" alt="postmessage 2"></p>