Implemented WaitForInputIdle.

diff --git a/include/callback.h b/include/callback.h
index 44a49a0..7bf4343 100644
--- a/include/callback.h
+++ b/include/callback.h
@@ -103,6 +103,7 @@
     HQUEUE16 WINAPI (*InitThreadInput16)( WORD unknown, WORD flags );
     void WINAPI (*UserYield16)( void );
     WORD WINAPI (*DestroyIcon32)( HGLOBAL16 handle, UINT16 flags );
+    DWORD WINAPI (*WaitForInputIdle)( HANDLE hProcess, DWORD dwTimeOut );
     
 }  CALLOUT_TABLE;