Planner-list Automatic percents recounting?

Hello,

Why there is no automatic percent recounting? For example if I have
tasks in gnome planner:

  1. Make website 
  1.1. Make design (duration 1 day)
  1.2. Code administration (duration 1 day)

Then for 1st task "Make website" duration comes sum of subtasks
(in my example it will be 2 days). If I set Completed to 100% for
"Make design", my main task will be not updated (still with 0%). Is
there possible in any way to see how much work completed yet?

Thanks for reply (sorry, for poor English).

--- 
With best regards,
Remigijus