[Coresuite Designer] How to hide columns in a Select Grid

If you want to print or email many documents at once, the Select Grid is your tool of choice. How you define a Select Grid is explained in the coresuite manual here:  
http://helpfiles.coresystems.ch/help/country_package/manual/en/desref_ex4.htm

In the Select Grid, you maybe need a lot of columns to handle the layout printing, but the information included are of little help for the customer.

I prepared the following example Select Grid:

The red marked columns are needed for the layout as parameters. But as you can imagine, they are of little help for the user and it is not necessary to show these columns in the grid.

To hide this columns, I change the base query of the select grid. All columns with a name ending with the string literal '_ldi' (short for layout designer invisible) will be hidden. Here is the query:

SELECT 
 T0.DocEntry as "DocEntry_ldi", 
 DocNum,
 DocDate, 
 139 as "FormType_ldi", 
 T0.LangCode as "LangCode_ldi", 
 T1.[E_Mail] as email, 
 T1.[CardCode], 
 T1.[CardName] 
FROM ORDR T0 INNER JOIN OCRD T1 ON T0.CardCode = T1.CardCode

If I open the Select Grid again, It looks like that:

Afterwards, I have to to change the parameter definition as the Item Id needs to match the column name. otherwise, the layout printing won't work.