title: WM_MOUSEMOVE / wParam doesn't contain key state, only when any mouse button is pressed
body: <p>I use a WS_EX_LAYERED window and receive a WM_MOUSEMOVE message when the mouse moves over non-transparent areas. So far so good.</p>
  <ul>
  <li><p>When I press and hold SHIFT or CTRL and move the mouse, WM_MOUSEMOVE/wParam doesn't indicate the key state.</p>
  </li>
  <li><p>When I press and hold SHIFT or CTRL and ANY mouse buttons while moving the mouse, WM_MOUSEMOVE/wParam does indicate the key state.</p>
  </li>
  <li><p>When I click into the window (assuming to set focus) and hold SHIFT or CTRL, again, WM_MOUSEMOVE / wParam doesn't indicate the key state.</p>
  </li>
  </ul>
  <p>Any idea what's up here? I have the suspicion that it has something to do with the active focus state of the window.</p>