When one task depends on one or several other tasks, it can be reflected by indenting (creating sub-tasks). When a task has incomplete sub-tasks, it would be nice to have an option to disable the completion check-box of such composite task until all sub-tasks are done or deleted. Completion check box can be replaced by a little padlock icon to indicate that the task cannot be completed before the sub-tasks.
thank you very much for your suggestion, we appreciate your feedback.
A similar option is already available. You can add an asterisk * in front of the parent task and it will no longer have a checkbox. However, the checkbox won't reappear when all sub-tasks are completed, you'll then need to edit it and remove the asterisk.