Gtk.IconSource.prototype.set_size

function set_size(size:Number):void {
    // Gjs wrapper for gtk_icon_source_set_size()
}

Sets the icon size this icon source is intended to be used with.

Setting the icon size on an icon source makes no difference if the size is wildcarded. Therefore, you should usually call Gtk.set_size_wildcarded to un-wildcard it in addition to calling this function.