Find an other icon for the zone edit button

At the moment it's confusing since we think that we're going to edit a section.

• This button really need to be different from the edit section one.
• it's even better if this button follow the colourtheme colour to be applied to buttons.

A dynamic behaviour can also been think of :

• The button would not be present unless you highlight the area.
• The area would have a border + the edit button displayed somewhere.