Check the following image, how can I add this kind of bar to my own NSTableViews? Other uses are in the network preferences app. What\'s the magic trick to make this work?>
I don't think there is any "magic trick." This is something you will have to implement yourself.
It looks like a group of Gradient style NSButtons placed below the table view. An NSSegmentedControl in Small Square style would work too.
NSButtons
NSSegmentedControl