Duration based on links

I have 3 tasks.
Task 3 must begin when task 1 starts, and end when task 2 ends.
Is it possible to bind the duration based on those two dates ?

No, sorry, task dependencies do not change task durations in GanttProject.

Continuing the discussion from Duration based on links:

Hi Dmitry, this option would be interesting, is it possible to implement it?

Hello! Dmitry is right, using dependencies is not possible…

… but a summary task fulfills your requirement as shown in attachment.
find attached screenshot.