Rectangle ratio calculator

gistfile1.cs

using System;
using System.Text;
using NGettext;
using R7.Webmate.Xwt.Icons;
using R7.Webmate.Xwt.Text;
using Xwt;

namespace R7.Webmate.Xwt
{
    public class HelloWorldWidget : Widget
    {
        protected ICatalog T = TextCatalogKeeper.GetDefault();

        protected TextEntry txtWidth;

        protected TextEntry txtHeight;

        protected TextEntry txtCalculed;

        public HelloWorldWidget()
        {
            var vbox = new VBox();
            var lblWidth = new Label(T.GetString("Ширина:"));

            var lblHeight = new Label(T.GetString("Высота:"));

            var btnCalculed = new Button(T.GetString("Calculate"));

            txtWidth = new TextEntry();
            txtHeight = new TextEntry();
            txtCalculed = new TextEntry();

            btnCalculed.Clicked += btnCalculed_Clicked;

            vbox.PackStart(lblWidth, false, true);
            vbox.PackStart(txtWidth, false, true);
            vbox.PackStart(lblHeight, false, true);
            vbox.PackStart(txtHeight, false, true);
            vbox.PackStart(btnCalculed, false, true);
            vbox.PackStart(txtCalculed, false, true);

            vbox.Margin = Const.VBOX_MARGIN;
            Content = vbox;
            Content.Show();
        }


        static int GCD(int a, int b)
        {
            while (b != 0)
            {
                var t = b;
                b = a % b;
                a = t;
            }
            return a;
        }

        void btnCalculed_Clicked(object sender, EventArgs e)
        {
            var w = int.Parse(txtWidth.Text);
            var h = int.Parse(txtHeight.Text);
            var a = w;
            var b = h;

            var r = (w / GCD(a, b) + ":" + h / GCD(a, b)) ;
            txtCalculed.Text = r.ToString();
        }
    }
}

Rename the file to HelloWorldWidget.cs

var w = int.Parse (txtWidth.Text);
var h = int.Parse (txtHeight.Text);
var r = (float) w / h;
txtCalculed.Text = r.ToString ();

namespace R7.Webmate.Xwt
{
public class HelloWorldWidget : Widget
{
protected ICatalog T = TextCatalogKeeper.GetDefault ();

    protected TextEntry txtWidth;

    protected TextEntry txtHeight;

    protected TextEntry txtCalculed;

    public HelloWorldWidget()
    {
        var vbox = new VBox ();
        var lblWidth = new Label (T.GetString ("Ширина:"));

        var lblHeight = new Label(T.GetString("Высота:"));

        var btnCalculed = new Button (T.GetString ("Click me!"));

        txtWidth = new TextEntry  ();
        txtHeight = new TextEntry();
        txtCalculed = new TextEntry ();

        var w = int.Parse(txtWidth.Text);
        var h = int.Parse(txtHeight.Text);
        var r = (float) w / h;

        btnCalculed.Clicked += btnCalculed_Clicked;

        vbox.PackStart (lblWidth, false, true);
        vbox.PackStart (txtWidth, false, true);
        vbox.PackStart(lblHeight, false, true);
        vbox.PackStart(txtHeight, false, true);
        vbox.PackStart (btnCalculed, false, true);
        vbox.PackStart (txtCalculed, false, true);

        vbox.Margin = Const.VBOX_MARGIN;
        Content = vbox;
        Content.Show ();
    }

    void btnCalculed_Clicked(object sender, EventArgs e)
    {
        txtCalculed.Text = r.ToString ();
    }
}

}

Basic error: "Имя "r" не существует в данном контексте". Because of this, the program cannot start.

var w = int.Parse (txtWidth.Text);
var h = int.Parse (txtHeight.Text);
var r = (float) w / h;
txtCalculed.Text = r.ToString ();

А первые три строчки? Видимо, невидимые чернила...

И не нужно дублировать весь код в комментариях - обновляете сам gist, там есть история версий (revisions) - см. мой форк.