Index: openacs-4/packages/acs-templating/tcl/head-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-templating/tcl/head-procs.tcl,v
diff -u -N -r1.45.2.8 -r1.45.2.9
--- openacs-4/packages/acs-templating/tcl/head-procs.tcl	22 Apr 2019 19:19:57 -0000	1.45.2.8
+++ openacs-4/packages/acs-templating/tcl/head-procs.tcl	12 May 2019 11:20:43 -0000	1.45.2.9
@@ -1068,11 +1068,16 @@
     @author  Gustaf Neumann
 } {
     set prevent [expr {$preventdefault_p ? "event.preventDefault();" : ""}]
-
-    set script [subst {
-        e.addEventListener('$event', function (event) {$prevent$script}, $usecapture_p);
-    }]
-
+    if {!$preventdefault_p && [regexp {^\s*([a-zA-Z0-9_]+)[\(]event[\)];\s*} $script . fn]} {
+        #
+        # In the most simple case, there is no need for a wrapper function.
+        #
+        set script [subst {e.addEventListener('$event', $fn, $usecapture_p);}]
+    } else {
+        set script [subst {
+            e.addEventListener('$event', function (event) {$prevent$script}, $usecapture_p);
+        }]
+    }
     if {[info exists id]} {
         set script [subst {
             var e = document.getElementById('$id');