Thanks.
The problem is related with Designer.
Ok, I have a pure QWidget.
I have 1.- a List 2.- a Treeview. I want to apply a horizontal layout to this two elements, givin (in example ) 200 pixels max to treeview. I select the 2 components and click on 'layout Horizontally".Ok, my horizontal resize runs ok.

I have my third element, a 'floating' widget that I have placed in no particular place, in example, at the bottom -left.
Next, I want to let automatic vertical resize for my 2 main componentes (the list and the treeview), so on the main Widget I choose layout vertically.

The problem was that this layout is applying to the layout_horizontal and my_floating widget.
And I dont know how to fix this problem ?
The solution can be a bool 'float' property that does not exist. ( to tell layout that a widget with this property set to true is not part of the world to adjust )
Thanks