Index: openacs-4/packages/forums/www/message-post.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/forums/www/message-post.tcl,v
diff -u -r1.43.2.3 -r1.43.2.4
--- openacs-4/packages/forums/www/message-post.tcl	1 Jun 2016 21:24:41 -0000	1.43.2.3
+++ openacs-4/packages/forums/www/message-post.tcl	26 Sep 2016 18:48:55 -0000	1.43.2.4
@@ -11,19 +11,18 @@
     {parent_id ""}
 } -validate {
     forum_id_or_parent_id {
-      if {$forum_id eq "" && $parent_id eq ""} {
-	ad_complain [_ forums.lt_You_either_have_to]
-      }
-      #
-      # GN: why can't we use {forum_id:integer ""} above? if we do so, the
-      # forum_id is not set!
-      #
-      if {$forum_id ne "" && ![string is integer $forum_id]} {
-	ad_complain [_ acs-templating.Invalid_integer]
-      }
-      if {$parent_id ne "" && ![string is integer $parent_id]} {
-        ad_complain [_ acs-templating.Invalid_integer]
-      }
+        if {$forum_id eq "" && $parent_id eq ""} {
+          ad_complain [_ forums.lt_You_either_have_to]
+        }
+        if {$forum_id ne "" && ![string is integer $forum_id]} {
+            ad_complain [_ acs-templating.Invalid_integer]
+        }
+        if {$forum_id ne "" && ![forum::valid_forum_id_p -forum_id $forum_id]} {
+            ad_complain [_ acs-templating.Invalid_integer]
+        }
+        if {$parent_id ne "" && ![string is integer $parent_id]} {
+            ad_complain [_ acs-templating.Invalid_integer]
+        }
     }
 }