Question: I'd like to mark a tableview row in some way that shows it has been clicked by the user. I have a large number of rows and want users to know if they have already visited a particular row. This same technique will be useful for identifying row new entries as well. 

I have two questions: Would such a subtle technique violate the HIGS and what would be a nice way to do it without muddying up the UI?

Answer: 
Perhaps you could have a colored dot like in Apple's Mail app:

![](https://lh4.ggpht.com/_yPwgXJ_OI8Y/SvtAD8cpm1I/AAAAAAAABSM/GZ_DzuSAb9I/s800/Screen%20shot%202009-11-11%20at%2011.51.20%20PM.png)

This obviously shouldn't violate HIGS.
Maybe you could use a subtle background colouring of the rows that have been already visited.