Steps to reproduce:

1. Create host.
2. Add global macro with long value.
3. Create item, put items name the same macro created in 2nd step.
4. Open dashboard and start adding graph widget.
5. Press on overrides tab.
6. Press on button select, next to item pattern.
7. Observe:
   
8. Add this long item.
9. Observe the changes on "Overrides" tab: