fix calculation of fillup columns for subtables

plugins/Actions/javascripts/actionsDataTable.js

@@ -318,7 +318,12 @@
 
             $('tr#' + idToReplace, root).after(response).remove();
 
-            var missingColumns = (response.prev().find('td').size() - response.find('td').size());
+            var requiredColumnCount = 0, availableColumnCount = 0;
+
+            response.prev().find('td').each(function(){ requiredColumnCount += $(this).attr('colspan') || 1; });
+            response.find('td').each(function(){ availableColumnCount += $(this).attr('colspan') || 1; });
+
+            var missingColumns = requiredColumnCount - availableColumnCount;
             for (var i = 0; i < missingColumns; i++) {
                 // if the subtable has fewer columns than the parent table, add some columns.
                 // this happens for example, when the parent table has performance metrics and the subtable doesn't.