C#

public class SingletonForm : System.Windows.Forms.Form
{
private System.ComponentModel.Container components = null;
private static SingletonForm formInstance;
public SingletonForm()
{
	InitializeComponent();
}
public static SingletonForm GetInstance()
{
	if(formInstance!=null)
		return formInstance;
	else
		return (formInstance =new SingletonForm());

}

protected override void Dispose( bool disposing )
{
	if( disposing )
	{
		if(components != null)
		{
			components.Dispose();
		}
		
	}
	base.Dispose( disposing );
}


private void InitializeComponent()
{
	this.components = new System.ComponentModel.Container();
	this.Size = new System.Drawing.Size(300,300);
	this.Text = "SingletonForm";
}

protected override void OnClosing(CancelEventArgs e)
{
	e.Cancel=true;
	this.Hide();
}
}

private string GetWordFromPos(Point p)
{
	string word;
	int cIdx=richTextBox1.GetCharIndexFromPosition(p);
	//go left
	int startPos;
	for(startPos=cIdx;startPos>0;startPos--)
	{
		string c=richTextBox1.Text.Substring(startPos-1,1);
		if(c == " ") // add more seperator check here
			break;
	}
	//get the left part
	word=richTextBox1.Text.Substring(startPos,cIdx-startPos);
	//go right
	for(startPos=cIdx;startPos<richTextBox1.Text.Length;startPos++)
	{
		string c=richTextBox1.Text.Substring(startPos,1);
		if(c == " ")// add more seperator check here
			break;
	}
	word+=richTextBox1.Text.Substring(cIdx,startPos-cIdx);
	return word;
}
private void richTextBox1_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
{
  	Point p=new Point(e.X,e.Y);
	String word=GetWordFromPos(p);
	Debug.WriteLine(word);
}

Console.WriteLine("Press Enter to continue...");
Console.ReadLine();