+/*
+// TODO : layering & drawing loop
+1) browse tree and calculate 'size' for SIZE_BY_CONTENT
+ - SIZE_BY_CONTENT loop calculate child first
+ - if 'size' changed then 'resize = 1' on the parent (tester resize aprés la boucle)
+ - size == width on horizontal panel and == height on vertical panel
+2) browse tree and calculate 'size' for SIZE_BY_LAYOUT
+ - SIZE_BY_LAYOUT loop calculate parent first
+ - if 'size' changed then 'resize = 1' on childs with SIZE_BY_LAYOUT
+ - calculate width = size - somme(child_with_of_SIZE_BY_CONTENT) modulo(number of child_SIZE_BY_LAYOUT)
+ - calculate modulo =
+3) calculate posx of all objects
+4) redraw needed objects
+*/
+