c# How to use the ProcessDialogKey to capture special characters like "Tab", "Up" etc...

Answer 1

Your code is working, you message box is just displaying the tab character i.e. blank space.

Cast to int and you will see it's working:

MessageBox.Show("button: " + (int) e.KeyChar);

EDIT: Otherwise look at this code:

public Form1()
{
    InitializeComponent();

    this.KeyPress += new KeyPressEventHandler(this.Form1_KeyPress);
    this.KeyDown += new KeyEventHandler(this.Form1_KeyDown);            
}

// Keypress only handles keys in the ascii range
private void Form1_KeyPress(object sender, KeyPressEventArgs e) 
{ 
    MessageBox.Show("KeyPress: " + (int) e.KeyChar); 
}

// Keydown will work for all keys
private void Form1_KeyDown(object sender, KeyEventArgs e)
{
    MessageBox.Show("KeyDown: " + e.KeyCode); 
}