I asked this question a few days ago and no one replied.
It was about vanishing of the DataGrid's right border when
one of columns is hidden.
I found where is the problem, but no ideas how to fix it.
Because I'm not a designer, I used an auto-format feature
of the DataGrid editor. There's Professional 2 style and
I choosed it for my grid.
Create a new page, put DataGrid on it, select Professional 2
format, create a few template columns, set Visible of one
of them to false and the right border disappears.
How to fix this?