After a pause with Arduino, I installed 1.8.5 version of the IDE. Then I tested an example for DUE with it. After Verify I got this
Archiving built core (caching) in: C:\Users\LM7\AppData\Local\Temp\arduino_cache_5856\core\core_arduino_sam_arduino_due_x_dbg_2827dcfd51d4742e208ca5016f11e495.a
Sketch uses 54144 bytes (10%) of program storage space. Maximum is 524288 bytes.
Should I be worried, if not, why it is in red.