Block datagrid selection without losing line selections

Hello there,

  I want to block line selection for a Datagrid without losing the previous selection:

     1st - Select X rows.

     2nd - block the Datagrid keeping the selection and keep the scrolls working.

  I tried the IsEnable = false but it clears the selected items.

  I'd like something like IsHitTestVisual = false but with the ScrollViewer still working.

thanks in advance.

-- Jorge_M_P