Lock widgets in kmail

Hi,

is there a way to lock the widgets of the UI of kmail so that they cannot be 
changed? I set up a Kubuntu laptop for my father-in-law, but he more and more 
messes up the widgets and then don't know how to fix it. I would like to 
freeze kmail so he can only create emails, open emails and switch folders. 
Changing the toolbars, columns width and so on should not be possible.

Thanks & regards,

mls

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