Single Page Application

[alonfnt]

I believe that the guidelines say that a single page application shouldn't have a visible header. However this is not always applied.

I think if a single page switch is added to the new app configuration

it would help create more consistent apps. The final look would be

and in order to achieve this, we only need to replace this block of code in the activate method in Application.vala

window.title = "Single Page Application";
window.set_default_size (900, 640);
window.add (main);
window.show_all ();

for

window.set_default_size (900, 640);
          
var titlebar = new Gtk.HeaderBar ();
titlebar.title = "Single Page Application";
titlebar.show_close_button = true;
titlebar.has_subtitle = false;
var titlebar_style_context = titlebar.get_style_context ();
titlebar_style_context.add_class (Gtk.STYLE_CLASS_FLAT);
            
window.add (main);
window.set_titlebar (titlebar);

so developers don't have to look for the Gtk Style class and so.

Thoughts?

[OctoD]

It would be a good idea, could you please open a PR for it? Thanks!