It doesn't make sense to keep them separate as GtkSizeRequest requires a GtkWidget and GtkWidget implements GtkSizeRequest, so you can never have one without the other. It also makes the code a lot easier because no casts are required when calling functions. Also, the names would translate to gtk_widget_get_width() and people agreed that this would be a too generic name, so a "preferred" was added to the names. So this patch moves the functions: gtk_size_request_get_request_mode() => gtk_widget_get_request_mode() gtk_size_request_get_width() => gtk_widget_get_preferred_width() gtk_size_request_get_height() => gtk_widget_get_preferred_height() gtk_size_request_get_size() => gtk_widget_get_preferred_size() gtk_size_request_get_width_for_height() => gtk_widget_get_preferred_width_for_height() gtk_size_request_get_height_for_width() => gtk_widget_get_preferred_height_for_width() ... and moves the corresponding vfuncs to the GtkWidgetClass. The patch also renames the implementations of the vfuncs in widgets to include the word "preferrred".