print vertexs working
refactorized presentation and business controler: created class PresentationArea
displaying and hidding areas working
share vertexs are colored with the areas' RGB color sum
shared vertexs are colored with transparency
shared vertexs are colored with substractive color mixing
shared vertexs are colored with alternative color concentric circles
shared vertexs are colored with one concentric sphere for area. definite version for now.
fix: when a hidden area is selected, the display button is automatically marked