Question

I am overriding ProcessCmdKey in a control like this:

protected override bool ProcessCmdKey(ref Message msg, Keys keyData) {
    if ((keyData & Keys.Up) == Keys.Up)
        MessageBox.Show("Up arrow");
    else if ((keyData & Keys.Right) == Keys.Right)
        MessageBox.Show("Right arrow");

    // it doesn't matter what I return, the glitch happens anyway
    return base.ProcessCmdKey(ref msg, keyData);
}

And when I press the Up arrow key, the message Up arrow appears, but it also appears when I press the Right arrow key. Why is this?

Answer 1

Read the comment above for a description of the problem.

protected override bool ProcessCmdKey(ref Message msg, Keys keyData) {
    if (keyData == ((Keys)(Keys.Shift | Keys.Up)))
        MessageBox.Show("Up arrow");
    else if (keyData == Keys.Right)
        MessageBox.Show("Right arrow");

    // it doesn't matter what I return, the glitch happens anyway
    return base.ProcessCmdKey(ref msg, keyData);
}

You don’t even need to cast it, because the argument is passed in as a key. So you can compare the two enums just like you would two strings or integers.