QTreeWidget: Mouse dragging not handled in branches

In a QTreeWidgets with several items, expand one of the items and click and hold pressed the left mouse button on one of the children (in the middle of the item text ). Now, with the mouse button still pressed, move the mouse up and down and see how the current item follows the mouse cursor. While moving the mouse up and down, gradually move it to the left. As soon as the mouse cursor enters the area of the tree branches, the up/down movements no longer make the current item follow the mouse cursor.