TargetIsReadOnly
item->SetEnabled(HasSelection() && TargetIsReadOnly() == false);
item->SetEnabled(!(IsRoot() || IsTrash() || InTrash()) && TargetIsReadOnly() == false);
item->SetEnabled(TargetIsReadOnly() == false);
bool isPastable = FSClipboardHasRefs() && TargetIsReadOnly() == false
bool TargetIsReadOnly() const;