Apple has many task specific controls built into Cocoa. They are all well designed and have most of the functionality a user and a developer expect. One of this controls is the NSSearchField. This control has a special design which allows the user to recognize the provided functionality with ease. It is so well-known that Apple uses the design even on there website. It has support for menus (e.g. for recent search items), auto completion, a cancel button, and so one. Although this is mostly feature complete, there are sometimes cases where you like to extend it. In this post, I will show how to add another visual hint to this control when a search term isn’t found. The aim is to change the background of the underlying text edit to become light red to visual mark the failed search.