Thanks for contacting Syncfusion support.
Please find the response for your queries below,
Query 1: while drag and drop the task node it has to ask confirmation message .If i click "cancel" button it has to be not allowed to drag to the next position
You can achieve this requirement by handling NodeDragCompleted Event. The following code snippet will illustrate this,
private void Gantt_NodeDragCompleted(object sender, NodeDragAndDropEventArgs args)
MessageBox.Show("Update", "GanttMessage", MessageBoxButton.OKCancel);
if (DialogResult != true) //OK
//the position of the nodes cannot be changed and come back to the previous Position
Query 2: How to avoid overlapping of task nodes.
You can achieve this requirement by handling NodeDragCompleted and NodeResizingCompleted events. We created the sample for this requirement and please check the sample from following link,
Please let us know if you need further assistance.
Riyaj Ahamed I