Gtk.Window.prototype.set_geometry_hints

function set_geometry_hints(geometry_widget:Gtk.Widget, geometry:Gdk.Geometry, geom_mask:Gdk.WindowHints):void {
    // Gjs wrapper for gtk_window_set_geometry_hints()
}

This function sets up hints about how a window can be resized by the user. You can set a minimum and maximum size; allowed resize increments (e.g. for xterm, you can only resize by the size of a character); aspect ratios; and more. See the Gdk.Geometry struct.