Edit.
About script 1.3 view_tasks.php
Question1: How can the code below see if the task has a subtask by looking at the task's task_id?
Question2: Is there a way to determine if the task's parent_id=0 inside the foreach? (I want to add a link to each Main task)
// Check for subtasks:
if (isset($tasks[$task_id])) {
// Call this function:
make_list($tasks[$task_id]);
}