Sets up the icon representing a. The icon is used when the window is minimized (also known as iconified). Some window managers or desktop environments may also place it in the window frame, or display it in other contexts. gtk_window_set_icon_list() allows you to pass in the same icon in several hand-drawn sizes. The list should contain the natural sizes your icon is available in; that is, don't scale the image before passing it to GTK+. Scaling is postponed until the last minute, when the desired final size is known, to allow best quality. By passing several sizes, you may improve the final image quality of the icon, by reducing or eliminating automatic image scaling. larger images (64x64, 128x128) if you have them. See also gtk_window_set_default_icon_list() to set the icon for all windows in your application in one go. Note that transient windows (those who have been set transient for another window using gtk_window_set_transient_for()) will inherit their icon from their transient parent. So there's no need to explicitly set the icon on transient windows.