Yes, that's clear :P my problem is, for instance: these two arrows are in the same scene but their scene positions are the same.

If I understand right, The scene represents the base coordinate system for all its items. The scene coordinate system describes the position of each top-level item, and also forms the basis for all scene events delivered to the scene from the view I have a problem because what's happening in my code is not possible.



More or less I solved it with mapToScene and mapFromScene... but when I try something more complicated it becomes crazy:

For example, I have two connected arrows (the finish of the first is aiming to the beginning of the second), they are different items so I get their coordinates with mapToScene and, from another object, I paint them using their coordinates (two QPoints for each arrow, the starting point and the finishing point, four in total) and mapFromScene.

Ok, this works fine... but when I create a QGraphicsItemGroup and I add both arrows, when I move that group the beginning of the third point (the starting point of the second arrow) becomes crazy again (the other three work fine, that's what I don't understand).

If I don't move the group, the coords are right. That's why I think I have done something strange in my code and my scene is not working properly.