If you delete item that is a master item for other dependent items - they are all deleted without any warning or even notice with all data collected. All you have is this:

There is no 'Details' button to find out that months of history collected is gone with dependent items attached.
Situation could get worse if ZBXNEXT-4200 is implemented.

Suggested:

• Provide confirmation request from user for master item delete if there are dependent items present (not going to help if mass operation is used)
• At least list those dependent items as deleted in green notification line