gtk:window-icon-name (object)

object -- a gtk:window widget
name -- a string for the name of the themed icon

The accessor for the icon-name slot of the gtk:window class gets or sets the name of the themed icon for the window. See the gtk:icon-theme documentation for more details. On some platforms, the window icon is not used at all.

Note that this has nothing to do with the WM_ICON_NAME property which is mentioned in the Inter-Client Communication Conventions Manual (ICCCM).