title: How to discard some messages for a window?
body: <p>My goal is to disable some tool-tip-like thing in window of another process. My thoughts are to block <code>WM_MOUSEMOVE</code> if the coordinates of mouse movement is in certain rectangle of the window.</p>
  
  <p>I can use <code>SetWindowsHookEx</code> to receive that messages (<code>WH_CALLWNDPROC</code> and <code>WH_GETMESSAGE</code>), but it doesn't allow to block them. I can return 1 instead of calling <code>CallNextHookEx</code>, but it doesn't prevent WndProc of window to receive the message. However, this approach works for blocking events in MOUSE_LL/KEYBOARD_LL.</p>
  
  <p><code>SetWindowsHookEx</code> is also not good, because it installs hook to all windows across the system.</p>
  
  <p>How I can prevent window of another process from receiving certain windows messages?</p>