Gtk.Widget.prototype.size_request

function size_request():void {
    // Gjs wrapper for gtk_widget_size_request()
}

This function is typically used when implementing a Gtk.Container subclass. Obtains the preferred size of a widget. The container uses this information to arrange its child widgets and decide what size allocations to give them with Gtk.Widget.prototype.size_allocate.

You can also call this function from an application, with some caveats. Most notably, getting a size request requires the widget to be associated with a screen, because font information may be needed. Multihead-aware applications should keep this in mind.

Also remember that the size request is not necessarily the size a widget will actually be allocated.