Example of customizing shortcut keys in C# WinForm, _PHP tutorial

private void keyDown(object sender, KeyEventArgs e)
{
StringBuilder keyValue = new StringBuilder();
​ keyValue.Length = 0;
​ keyValue.Append("");
If (e.Modifiers != 0)
{
           if (e.Control)
              keyValue.Append("Ctrl + ");
If (e.Alt)
              keyValue.Append("Alt + ");
If (e.Shift)
              keyValue.Append("Shift + ");
}
If ((e.KeyValue >= 33 && e.KeyValue <= 40) ||
(e.KeyValue >= 65 && e.KeyValue <= 90) || //a-z/A-Z
(e.KeyValue >= 112 && e.KeyValue <= 123)) //F1-F12
{
         keyValue.Append(e.KeyCode);
}
else if ((e.KeyValue >= 48 && e.KeyValue <= 57)) //0-9
{
         keyValue.Append(e.KeyCode.ToString().Substring(1));
}
This.ActiveControl.Text = "";
//Set the text content of the current active control
This.ActiveControl.Text = keyValue.ToString();
}

private void keyUp(object sender, KeyEventArgs e)
{
String str = this.ActiveControl.Text.TrimEnd();
int len ​​= str.Length;
If (len >= 1 && str.Substring(str.Length - 1) == "+")
{
This.ActiveControl.Text = "";
}
}

private void textBox1_KeyDown(object sender, KeyEventArgs e)
{
KeyDown(sender, e);
}

private void textBox1_KeyUp(object sender, KeyEventArgs e)
{
KeyUp(sender, e);
}