KeyEventArgs (Clase)

private void textBox1_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
{
    // Determine whether the key entered is the F1 key. If it is, display Help.
    if(e.KeyCode == Keys.F1 && (e.Alt || e.Control || e.Shift))
    {
        // Display a pop-up Help topic to assist the user.
        Help.ShowPopup(textBox1, "Enter your name.", new Point(textBox1.Bottom, textBox1.Right));
    }
    else if(e.KeyCode == Keys.F2 && e.Modifiers == Keys.Alt)
    {
        // Display a pop-up Help topic to provide additional assistance to the user.
        Help.ShowPopup(textBox1, "Enter your first name followed by your last name. Middle name is optional.",
            new Point(textBox1.Top, this.textBox1.Left));
    }
}

    // This example demonstrates how to use the KeyDown event with the Help 
    // class to display pop-up style help to the user of the application.
    // The example filters for all variations of pressing the F1 key with
    // a modifier key by using the KeyEventArgs properties passed to the
    // event handling method.When the user presses any variation of F1 that
    // includes any keyboard modifier, the Help class displays a pop-up window,
    // similar to a ToolTip, near the control. If the user presses ALT + F2,
    // a different Help pop-up is displayed with additional information.
    // This example assumes that a tTextBox control, named textBox1, has been
    // added to the form and its KeyDown event has been contected to this 
    // event handling method.
    private void textBox1_KeyDown(Object sender,
        System.Windows.Forms.KeyEventArgs e)
    {
        // Determine whether the key entered is the F1 key.
        //If it is, display Help.
        if (e.get_KeyCode().Equals(Keys.F1) && (e.get_Alt() || e.get_Control() 
            || e.get_Shift())) {
            // Display a pop-up Help topic to assist the user.
            Help.ShowPopup(textBox1, "Enter your name.", new Point(textBox1.
                get_Bottom(), textBox1.get_Right()));
        }
        else {
            if (e.get_KeyCode().Equals(Keys.F2) && e.get_Modifiers().
                Equals(Keys.Alt)) {
                // Display a pop-up Help topic to provide additional assistance
                // to the user.
                Help.ShowPopup(textBox1, "Enter your first name followed by" 
                    + " your last name.Middle name is optional.",new Point(
                    textBox1.get_Top(), this.textBox1.get_Left()));
            }
        }
    } //textBox1_KeyDown
} //Form1

private void treeView1_KeyDown(object sender, KeyEventArgs e)
{
   /* If the 'Alt' and 'E' keys are pressed,
      * allow the user to edit the TreeNode label. */
   if(e.Alt && e.KeyCode == Keys.E)

   {
      treeView1.LabelEdit = true;
      // If there is a TreeNode under the mose cursor, begin editing. 
      TreeNode editNode = treeView1.GetNodeAt(
         treeView1.PointToClient(Control.MousePosition));
      if(editNode != null)
      { 
         editNode.BeginEdit();
      }
   }
}

private void treeView1_AfterLabelEdit(object sender, NodeLabelEditEventArgs e)
{
   // Disable the ability to edit the TreeNode labels.
   treeView1.LabelEdit = false;
}

private void treeView1_KeyDown(Object sender, KeyEventArgs e)
{
    /* If the 'Alt' and 'E' keys are pressed,
       allow the user to edit the TreeNode label. 
     */
    if (e.get_Alt() && e.get_KeyCode() == Keys.E) {
        treeView1.set_LabelEdit(true);
        // If there is a TreeNode under the mose cursor, begin editing. 
        TreeNode editNode = treeView1.GetNodeAt(treeView1.PointToClient(
            Control.get_MousePosition()));
        if (editNode != null) {
            editNode.BeginEdit();
        }
    }
} //treeView1_KeyDown

private void treeView1_AfterLabelEdit(Object sender, 
    NodeLabelEditEventArgs e)
{
    // Disable the ability to edit the TreeNode labels.
    treeView1.set_LabelEdit(false);
} //treeView1_AfterLabelEdit

// Boolean flag used to determine when a character other than a number is entered.
private bool nonNumberEntered = false;

// Handle the KeyDown event to determine the type of character entered into the control.
private void textBox1_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
{
    // Initialize the flag to false.
    nonNumberEntered = false;

    // Determine whether the keystroke is a number from the top of the keyboard.
    if (e.KeyCode < Keys.D0 || e.KeyCode > Keys.D9)
    {
        // Determine whether the keystroke is a number from the keypad.
        if (e.KeyCode < Keys.NumPad0 || e.KeyCode > Keys.NumPad9)
        {
            // Determine whether the keystroke is a backspace.
            if(e.KeyCode != Keys.Back)
            {
                // A non-numerical keystroke was pressed.
                // Set the flag to true and evaluate in KeyPress event.
                nonNumberEntered = true;
            }
        }
    }
}

// This event occurs after the KeyDown event and can be used to prevent
// characters from entering the control.
private void textBox1_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
{
    // Check for the flag being set in the KeyDown event.
    if (nonNumberEntered == true)
    {
        // Stop the character from being entered into the control since it is non-numerical.
        e.Handled = true;
    }
}

// Boolean flag used to determine when a character other than a number 
// is entered.
private boolean nonNumberEntered = false;

// Handle the KeyDown event to determine the type of character entered 
// into the control.
private void textBox1_KeyDown(Object sender, 
    System.Windows.Forms.KeyEventArgs e)
{
    // Initialize the flag to false.
    nonNumberEntered = false;

    // Determine whether the keystroke is a number from the top of the 
    // keyboard.
    if ((e.get_KeyCode().CompareTo(Keys.D0)) < 0 
        || (e.get_KeyCode().CompareTo(Keys.D9) > 0)) {

        // Determine whether the keystroke is a number from the keypad.
        if ((e.get_KeyCode().CompareTo(Keys.NumPad0) < 0 
            || (e.get_KeyCode().CompareTo(Keys.NumPad9)) > 0)) {

            // Determine whether the keystroke is a backspace.
            if (!(e.get_KeyCode().Equals(Keys.Back))) {
                    // A non-numerical keystroke was pressed.
                    // Set the flag to true and evaluate in KeyPress event.
                    nonNumberEntered = true;
            }
        }
    }
} //textBox1_KeyDown

// This event occurs after the KeyDown event and can be used to prevent
// characters from entering the control.
private void textBox1_KeyPress(Object sender, System.Windows.Forms.
    KeyPressEventArgs e)
{
    // Check for the flag being set in the KeyDown event.
    if (nonNumberEntered == true) {
        // Stop the character from being entered into the control since 
        // it is non-numerical.
        e.set_Handled(true);
    }
} //textBox1_KeyPress