Gridview whose element template is also GridView, how to fix column width?

Question

Windows

There is a GridView whose element template is also GridView, the parent GridView has only one column, but an unlimited number of columns.
The problem is that when adding an element to the nested GridView, its width may increase, which in turn, the width of all columns of the parent GridView is not the desired behavior, how to make sure that the width of the columns of the parent GridView is not recalculated?

Answer 1

In order not to be recalculated, specify it explicitly. No "*" and "Auto".

Answer 2

Most likely, you receive invalid JSON from the client (js), which is what the error says.
It's hard to help without details.