At first it was F.lux. Then came Redshift (inspired by F.lux) which also got a GTK version but only for switching it on/off. And now, a Redshift fork called RedshiftGUI finally brings a GUI for customizing everything. But what are these? All the applications mentioned above serve only one purpose: to change the color temperature of your screen by the time of day, making it easy for your eyes. This is achieved by entering your location and then Redshift (in the case of this post: RedshiftGUI) takes care of the rest.