* Area manage the background and border drawing, size and padding.
* Each Area have 2 Pixmap (pix and pix_active).
*
-* Area also manage the tree of visible objects. Parent object drawn before child object.
+* Area manage the tree of all objects. Parent object drawn before child object.
* panel -> taskbars -> tasks
* -> systray -> icons
* -> clock
// list of child : Area object
GSList *list;
+ int visible;
// need compute position and width
int resize;
// need redraw Pixmap