If you select the last task in the gantt and press enter. A new task will be created.
Where can I ask about customizing this action? And can it be turned off.
Support Forum
Please check this : https://www.bryntum.com/docs/gantt/api/Gantt/feature/CellEdit#config-addNewAtEnd
You can use it like this :
features : {
cellEdit : {
addNewAtEnd : false
}
}