better fontsize management

Fltk/GUI.cpp

Fltk/GUI.h

Fltk/aboutWindow.cpp

Fltk/aboutWindow.h

Fltk/classificationEditor.cpp

Fltk/clippingWindow.cpp

Fltk/clippingWindow.h

Fltk/colorbarWindow.cpp

Fltk/contextWindow.cpp

Fltk/contextWindow.h

Fltk/extraDialogs.cpp

Fltk/fieldWindow.cpp

Fltk/fieldWindow.h

Fltk/fileDialogs.cpp

Fltk/graphicWindow.cpp

Fltk/graphicWindow.h

Fltk/manipWindow.cpp

Fltk/manipWindow.h

Fltk/menuWindow.cpp

Fltk/menuWindow.h