"Z-grid" layout in special form

[Andrea Checchia]

I created a special form with the opening of 4 frames.

The result I would like to see is this

But unfortunately, I have this for the moment

I created the form by code and the 4 frames set up through a grid; But it does not work, why not?

Below the code

Is there a solution to this, please?

Thanks in advance.

Andrew