onBeforeRollupTaskDisplay

fires before the rollup task is displayed on its parent project

boolean onBeforeRollupTaskDisplay(number|string taskId,Task task,number|string parentId);

taskId	number\|string	the rollup task id
task	Task	the rollup task object
parentId	number\|string	the id of the parent (project) task

boolean

defines whether the rollup task will be displayed on its parent project (true) or not (false)

gantt.attachEvent("onBeforeRollupTaskDisplay", function(taskId, task, parentId){
    // any custom logic here
    return false;
});