bold text in vala

mytv.vala

using Gtk;

// valac --pkg gtk+-3.0 mytv.vala

public class MarkupTextView : TextView {
	public void append_text (string s) {
		TextIter end_iter;
		buffer.get_end_iter (out end_iter);
		buffer.insert_with_tags_by_name (ref end_iter, s, -1, null);
	}
	
	public void append_tagged_text (string s, string t) {
		TextIter end_iter;
		buffer.get_end_iter (out end_iter);
		buffer.insert_with_tags_by_name (ref end_iter, s, -1, t, null);
	}
}

public static int main (string[] args) {
	Gtk.init (ref args);
	
	var window = new Window ();
	window.set_default_size (400, 600);
	var text_view = new MarkupTextView ();
	text_view.editable = false;
	//this.text_view.cursor_visible = false;
	var mybold_tag = new TextTag ("mybold");
	mybold_tag.weight = Pango.Weight.BOLD; //https://valadoc.org/pango/Pango.Weight.html
	text_view.buffer.tag_table.add(mybold_tag);
//	text_view.buffer.create_tag ("bold", mybold_tag, null);
	
	text_view.append_text("hello\nworld!\nand ");
	text_view.append_tagged_text("**bye**", "mybold");
	text_view.append_text("; btw\n!");
	var scroll = new ScrolledWindow (null, null);
	scroll.set_policy (PolicyType.AUTOMATIC, PolicyType.AUTOMATIC);
	scroll.add (text_view);
	window.add (scroll);
	window.destroy.connect (Gtk.main_quit);
	window.show_all ();
	
	Gtk.main ();
	return 0;
}