Broken: Since dawn of time ;-)
Short description of error
Manually entering a value coming from 0, always reverts to 3
Exact steps for others to reproduce the error
Change Depth of Field Number of blades from default value 0 to 5
Observe Number of blades returns to 3
(when using the buttons on either side to increase the value from 0 to 5 it works, but who does that ;-)
My proposal is this:
Enter value manually or via mouse clicks: result cannot have other value than 0,3,4,5,6,...
If a user decides to enter a wrong value (1 or 2) it depends on what the previous value was. If it was higher it will enter 3, if it was 0 it stays 0.