flipselector item destructor had a severe drawback and this patch fixes it.
when deleting multiple items at once, the view needs to be updated only once.
however, the destructor updated the view on deletion of
every single item and it caused a severe performance issue.
the worst case happened when deleting a flipselector object -
with 10000 items, it took 10 seconds to finish deletion.
this patch has two points:
1. if a flipselector object is on deletion, item destructor doesn't update the view
2. otherwise, view update is handled in one job for multiple item deletion
Shinwoo Kim
Jaeun Choi
Tom Hacohen
Yeshwanth Reddivari
Cedric BAIL