In some countries you print a large number of copies (as stated by Pieter Naaijkens), in some only a single digit number which should then be distributed to a specific set of recipients. Regardless it is not unusual that a person might distribute copies to people that might have some interest in it. It is, however, not a must and the recipients is up to the author. When you send a thesis I think it is wise to write an accompanying letter explaining why the thesis is sent to the specific person. To send them without such a personal note may come across as a little odd and can of course be misunderstood. 

I did my PhD in the US and made a larger number of cheap copies (do not remember how many) to distribute among friends. I sent a few to others whose research I had built on. This was outside of the, at least then, mandatory five bound copies. In Sweden, where I now reside, printing of about 250 is mandatory and the student can print additional copies at their own cost. We recommend students to think about sending their thesis to people they can imagine would be interested in it. Since the life time of a thesis is usually quite short, most will soon be properly published, it is a good way to advertise your PhD and your work right after you have completed the work.

Is it usual for finished PhD students to send out physical copies of their thesis to unknown persons?
I use a TextChanged-EventHandler
I wrote a program in c# that creates a new TextBox on every button1_Click event
Now,I want each new TextBox (which was created) to show typed text.
How can I do this with EventHandler(TextChanged)?

namespace WindowsFormsApplication5
{
    public partial class Form1 : Form
    {
        Int32 i = 1;

    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        TextBox c = new TextBox();
        this.Controls.Add(c);
        c.Name = "x" + i.ToString();
        c.Left = 3;
        c.Top = 30 * i;
        i++;
        c.TextChanged += new EventHandler(c_TextChanged);


    }

    void c_TextChanged(object sender, EventArgs e)
    {
        textBox1.Text =           
    }

}
}

