user32: Add a stub implementation of ChangeWindowMessageFilter.

dlls/user32/message.c

@@ -3701,3 +3701,12 @@ BOOL WINAPI IsHungAppWindow( HWND hWnd )
     SERVER_END_REQ;
     return ret;
 }
+
+/******************************************************************
+ *      ChangeWindowMessageFilter (USER32.@)
+ */
+BOOL WINAPI ChangeWindowMessageFilter( UINT message, DWORD flag )
+{
+    FIXME( "%x %08x\n", message, flag );
+    return TRUE;
+}

dlls/user32/user32.spec

@@ -37,6 +37,7 @@
 @ stdcall ChangeDisplaySettingsW(ptr long)
 @ stdcall ChangeMenuA(long long ptr long long)
 @ stdcall ChangeMenuW(long long ptr long long)
+@ stdcall ChangeWindowMessageFilter(long long)
 @ stdcall CharLowerA(str)
 @ stdcall CharLowerBuffA(str long)
 @ stdcall CharLowerBuffW(wstr long)