SEASHELL_READONLY flag does not prevent pasting #890
Description
Pasting text (through CTRL+V or RMB+Paste) in a file marked with the comment // SEASHELL_READONLY will allow the change to go through. In the attached image, the following snippet was added to a "read-only" file:
#include <stdbool.h>
// SEASHELL_READONLY
// SEASHELL_READONLY
// For all of these functions:
// * you cannot mutate any
