Programming question - blinking cursor

On the seek tool, how do they do that?
I want to make a blinky thing like that, but how can I do it so steady like that. It looks to be 1hz, and the best i can do is 1/2 hz. Plus it looks pretty un affected by what's going on in the unit.

Many thanks in advance!

My guess would be a timer interrupt. This would probably be better asked in the programming forum, though...