Disable (Read-only) for sharepoint 2010/2013 People Picker (PeopleEditor)

Hi all,

I write in PageLoad-Method User to the PeoplePicker and it works.

Now I want prevent the user to delete the username which is in the PeoplePicker.

I use:

ppl.ShowButtons = false;
ppl.AllowTypeIn = false;
they works good but if I select the username press backspace it deletes it. Is there a workaround?

thanks in advance

BR
Ahmad

SP 2013 & SPD 2013 & VS 2013 & MSSQL 2012