Ensure pointers are put back to NULL when freed.

--Cette ligne, et les suivantes ci-dessous, seront ignorées--

M    trunk/palette.c
M    trunk/init.c
M    trunk/engine.c
M    trunk/filesel.c
M    trunk/miscfileformats.c
M    trunk/pages.c
M    trunk/brush_ops.c
M    trunk/op_c.c
M    trunk/operatio.c
M    trunk/brush.c
M    trunk/loadsave.c
M    trunk/graph.c
M    trunk/fileformats.c
M    trunk/main.c


git-svn-id: svn://pulkomandy.tk/GrafX2/trunk@1277 416bcca6-2ee7-4201-b75f-2eb2f807beb1

engine.c

@@ -1988,6 +1988,7 @@ void Close_popup(void)
   else
   {
     free(Window_background[Windows_open-1]);
+    Window_background[Windows_open-1] = NULL;
     Windows_open--;
   
     Paintbrush_hidden=Paintbrush_hidden_before_window;