Steps to reproduce:

1. Implement Semaphore-like status indicator using Graph Pie Diagram:
2. Create 3 calculated or dependent items, which change status from 0 to 1, or from 0 to 100 based on any specific calculation. Must have the same update interval. Only one item can be 1 or 100 at time, then others are 0.
3. Name created items accordingly: Status Green, Status Orange, Status Red.
4. Add all items to Semaphore Graph Pie Diagram.
5. So this supposed to work like a Semaphore Status Indicator and the entire circle should be colored by one of the colors: Green, Orange, Red. 

Result:

At first it will show fully colored pie diagram, green for example - which is correct.

Item values were:

Status Green value = 1

Status Orange value = 0

Status Red value = 0

But when after a minute items values changed:

Status Green value = 0

Status Orange value = 1

Status Red value = 0

Then Zabbix doesn't color the pie diagram fully and instantly upon item value change.

Instead of reflecting instant changes, like all other graph types do, it shows a 1-hour like slow coloring by orange, starting from right side clockwise.

The faulty Pie Graph update logic works the same slow in any other case, but in other cases it is harder to notice.

Expected:
The pie diagram graph must be updated whenever item values changes, instantly reflecting changes, like all other graphs work.

P.S: The ugly resolution/bit depth of Pie Diagram also could be fixed, to make it look smoother, like other graph type elements.

P.S.2: No need to show that ugly black line at right side, when pie diagram is fully colored (item value is 100%).