Steps to reproduce:

1. Monitoring latest data, click a graph of a single item
2. Select a 3 hour period from 9:00-12:00 to examine performance
3. Now select the same time interval exactly one week earlier to see if performance is indeed worse than 1 week before. 

Result:
Very difficult to choose the same time interval one week before. User has to select the precise time period or has to use time interval  as [now-5h-1w, now-1h-1w]. 
Expected:
UI offers a function to go back in time using specific jumps (1h, 1day, 1week), the same as it was in zabbix 3.