Impossible to edit UI in designer and c++ file at the same time on 2 different windows

Hello,

I'm working on a project where I would like to implement an UI to set complex way to sort/filter a model.
The model provide many data where I can set up a filter. I would like to have on my screens the definition of my model (.h or .cpp) and the ui form though the designer so I can create the perfect UI to filter on model data.

It seems impossible to have that because you can't split the view when you work with designer.

I tried adding another window and Qtcreator switches automatically to xml editor mode for ui file when cpp file editor on the other window get the focus.

Is there a way to have the widget designer and whatever we want on the other window without any conflict ?