Thank you for your respond, i removed the dot from the link.
The point is, i do not want to rearrange children of the GridContainer,
i just want to set the position of a GridContainer which is a child.
The strange thing with my project is:
Project instances have one own GridContainer and task instances also have one.
The positioning of the GridContainer of tasks works while that of the projects child GridContainer doesnt work.
-GridContainer (positioning false)
-GridContainer (positioning ok)
you can simply check this if you run the project, add 2 projects by clicking "+". Then attach 2 tasks to each of this projects by clicking "+" button of the projects and then do the same for the four tasks to add todos to each task. You will see that the tasks of project two will have an y-offset that todos of tasks will not have.