Comment 12 for bug 39482

in 93_upstream_nautilus-dnd-user-owned.patch inside the source package, there is already a patch that modified the behavior of nautilus_drag_default_drop_action_for_icons(..

I am thinking along the lines of something similar to that patch, to change the default behavior from move to copy when the source is readonly as in this bug's test case.

that would involve:
1) Creating a function using gnomevfs that checks if the source is readonly
2) add modifer to the " if (same_fs || target_is_source_parent)...." condition, as 93_upstream_nautilus-dnd-user-owned.patch already does.