as shown in the picture, an icon picker will help a user or a super user to update an icon (fontawesome or .png etc).
related to https://dev.tiki.org/item5783-Update-Menu-icons-to-use-fontawesome-icons-for-consistency-and-not-just-legacy-png-s

i don't know if there's some libraries or plugins for that, but i have done what's on the picture with some jquery and css
someone has an other idea?

I added a preference to choose to make the icons editable or not, look at the pictures below.
if it's "Y" the admin has the ability to edit an icon with an icon picker, I'm at the stage where i have to update the icon's name in the database

I suggest to make all icons editable for the Admin, thus he can edit an icon when he want.