Introduction
GUI development with Stetic (MonoDevelop's integrated GTK# visual designer). It 
will demonstrate how to create the layout of the GUI, how to add interactive 
elements to the layout and how to add functionality to the GUI.
Step 1: Create a new project 
Open monodevelop-->file menu-->new project  then 
![1.gif]()
For designer mode click right on solution
MainWindow from the
Solution Pad and select
Open
![d.gif]()
Step 2: Creating the GUI
To the Designer by pressing the "Designer" button located at the bottom
![3.gif]()
a) Adding containers empty Main window design 
![4.gif]()
Click to the view menu open Pads and select ToolBox  
![1.1.gif]()
Drag and drop the Vbox from the ToolBox,the main window looks like
![1.2.gif]()
Drag and drop the Hbox from the ToolBox,the main window looks like 
![1.3.gif]()
 
b) Adding Widgets from ToolBox
Add four buttons and textView to the Main Window 
![B.gif]() 
 
Step 3: Add functionality
![5.gif]()
Coding:
using System;
using System.IO;
using Gtk;
public
partial class
MainWindow : Gtk.Window
{
    public MainWindow()
        : base(Gtk.WindowType.Toplevel)
    {
        Build();
    }
    protected void 
OnDeleteEvent(object sender, DeleteEventArgs a)
    {
        Application.Quit();
        a.RetVal = true;
    }
    protected virtual
void clear(object 
sender, System.EventArgs e)
    {
        textview1.Buffer.Text = "";
    }
    protected virtual
void lower(object 
sender, System.EventArgs e)
    {
        textview1.Buffer.Text = textview1.Buffer.Text.ToLower();
    }
    protected virtual
void upper(object 
sender, System.EventArgs e)
    {
        textview1.Buffer.Text = textview1.Buffer.Text.ToUpper();
    }
    protected virtual
void save(object 
sender, System.EventArgs e)
    {
        StreamWriter sw =
new StreamWriter("file.txt");
        sw.Write(textview1.Buffer.Text);
        sw.Close();
    }
}
Step 4: Build All
![6.gif]()
Step 5: Run
Output : For  Lower case 
![OUT.gif]()
After pressing lower case button 
![O2.gif]()
 You can use same for other buttons also.