in website-creator/js/connectflows.js [324:334]
function checkClearAll(listBox, checkAll){
var lb;
if(listBox == 1)
lb = contactFlowsTable;
else
lb = contactFlowsTable2
lb.rows().every(function(index, element) {
var row = $(this.node());
$('input[type="checkbox"]', row).prop('checked', checkAll);
});
}