Peter,
I created a small sample app that hides and unhides a column in a Datagrid2. I will include details below. I am happy to share the sample app if that would be helpful.
Domain Model:
Microflow that creates or retrieves configuration object for each user. This is used to maintain specific configuration for different users.
Page with Datagrid 2
Microflow that is call by button entitled Toggle Visibility First Attribute
Note: this app will hide the column that is currently the first column displayed.
Hope that helps,
Mike