don't crash if no thread desktop set

reactos/subsys/win32k/ntuser

diff -u -r1.28 -r1.29
--- input.c	29 Apr 2004 20:26:35 -0000	1.28
+++ input.c	29 Apr 2004 20:41:03 -0000	1.29
@@ -16,7 +16,7 @@

  *  along with this program; if not, write to the Free Software
  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */

-/* $Id: input.c,v 1.28 2004/04/29 20:26:35 weiden Exp $

+/* $Id: input.c,v 1.29 2004/04/29 20:41:03 weiden Exp $

  *
  * COPYRIGHT:        See COPYING in the top level directory
  * PROJECT:          ReactOS kernel

@@ -477,7 +477,7 @@

   PW32THREAD OldBlock;
   ASSERT(W32Thread);
   

-  if(W32Thread->IsExiting && BlockIt)

+  if(!W32Thread->Desktop || (W32Thread->IsExiting && BlockIt))

   {
     /*
      * fail blocking if exiting the thread

@@ -541,8 +541,17 @@

   LPINPUT pInput,
   INT cbSize)
 {

+  PW32THREAD W32Thread;

   UINT cnt;
   

+  W32Thread = PsGetWin32Thread();
+  ASSERT(W32Thread);
+  
+  if(!W32Thread->Desktop)
+  {
+    return 0;
+  }
+  

   if(!nInputs || !pInput || (cbSize != sizeof(INPUT)))
   {
     SetLastWin32Error(ERROR_INVALID_PARAMETER);

@@ -554,7 +563,7 @@

    *         e.g. services running in the service window station cannot block input
    */
   if(!ThreadHasInputAccess(W32Thread) ||

-     !IntIsActiveDesktop(PsGetWin32Thread()->Desktop))

+     !IntIsActiveDesktop(W32Thread->Desktop))

   {
     SetLastWin32Error(ERROR_ACCESS_DENIED);
     return 0;