Why round-scale? Because a round scale is longer in 3.142 times than a line scale:-)
Have you ever seen round scales?
Every day while you see clocks ore watchers!
But you will spend a lot of time trying found such control in standard libraries;-)
It looks like programmer's world forgot something.
I did alarm clock with round scale interface.
One click is much better then 4-digit entering (hh:mm:-)
Do you want to see an example?
Go to http://www.brigsoft.com