GtkHRuler A horizontal ruler. The HRuler widget is a widget arranged horizontally creating a ruler that is utilized around other widgets such as a text widget. The ruler is used to show the location of the mouse on the window and to show the size of the window in specified units. The available units of measurement are GTK_PIXELS, GTK_INCHES and GTK_CENTIMETERS. GTK_PIXELS is the default. rulers. The #GtkHRuler struct contains private data and should be accessed with the functions below. Creates a new horizontal ruler. @Returns: the new GTKHRuler.